Onsen Tamago, or “hot spring eggs“ in Japanese, are slowly poached in the shell in volcanic hot spring water. This creates the most luxurious, silky egg whites and custard-like yolks. Learn how to make this delicious, easy recipe at home with my foolproof method.
Japan is world-famous for its 30,000+ natural hot springs or onsen. Visitors can take a relaxing and therapeutic bath at one of Japan‘s 3,000 onsen resorts and stay at a resort’s ryokan or traditional inn to experience their warm hospitality and delicious cuisine.
When I stay at a ryokan, one of their breakfast dishes that I eagerly anticipate is onsen tamago (温泉卵, “hot spring egg”). Why? Because this Japanese-style poached egg has the silkiest and creamiest texture. It‘s so comforting and satisfying to eat with hot steamed rice in the morning!
Back in the U.S., I find myself craving onsen tamago. Luckily, it’s easy to make this luxurious egg dish in your own kitchen. Whether you’re an onsen-tamago lover or first-time eater, let me show you my foolproof method today so you can make it at home anytime!
Table of Contents
What’s Onsen Tamago?
In Japanese, onsen means “hot spring” and tamago means “egg.” Onsen tamago (温泉卵), also known as ontama (温玉), is an egg that’s slow-poached in the shell using volcanic hot springs water.
What’s so special about these eggs? They are perfectly poached inside their shell, and the white is silky, creamy, and softer than the half-cooked yolk. This is the opposite of a typical poached egg cooked in simmering water, with a firm white and soft yolk.
The Chemistry Behind Onsen Tamago
We can achieve this special texture because the egg yolk and white solidify at different temperatures. The yolk solidifies at 158°F (70°C) and the white solidifies at 176°F (80°C).
To achieve perfect onsen tamago with creamy and silky whites and soft-cooked yolks, we must cook eggs in hot water at a constant temperature of 149–154°F (65–68°C) for 30 minutes or 154–158°F (68–70°C) for 20 minutes. This mimics the temperature of Japan’s volcanic hot spring waters.
Disclaimer: Many people in the world, including the Japanese, consume uncooked eggs in their cuisine. However, according to the FDA, eggs should be cooked to 165°F (74°C) in order to be considered safe. Please know that the perfect temperature for cooking onsen tamago is below the guideline. There is a risk of salmonella by consuming undercooked eggs.
Why This Recipe Works for Everyone
As we don’t have a steady supply of hot spring water at a constant temperature, here’s a method that works for typical home kitchens. This technique does not require special equipment like a microwave, thermometer, or sous vide machine (immersion circulator). It also does not use ice cubes for cooling the cooked eggs; this simplifies things, as some of you don’t keep ice cubes handy.
Here’s what you’ll need:
- A stove, a heavy-bottomed small pot, and a ladle (I use a fine-mesh skimmer). Why a heavy-bottomed pot? It retains heat better.
- Boiling water and tap water to create an ideal starting temperature for the cooking water.
- 4 refrigerated large eggs. Cold eggs offset the higher starting temperature of the cooking water. Some recipes require eggs at room temperature, but our readers’ kitchens have different temperatures depending on where they live, and I wanted to avoid the extra uncertainty.
If you follow my recipe precisely, you will achieve perfect onsen tamago as the final result. If you change the recipe, it will affect the water temperature and you may not achieve a perfect outcome.
🙋🏻♀️ Also, keep in mind that you can customize the firmness of the yolk by increasing or decreasing the cooking time.
How to Make Onsen Tamago
Here are the simple instructions on how to make perfect onsen tamago without a thermometer or immersion circulator.
- Prepare the cooking water: Boil 4¼ cups (1000 ml or 1 L) of water in a small heavy-bottomed pot. Once boiling, remove it from the stove. Add ¾ cup (200 ml) of cold tap water (65°F/18°C) to the boiled water.
- My hot water temperature at this stage was 180°F (82°C).
- Cook the eggs: Gently submerge 4 refrigerated large eggs, one at a time, in the hot water. Cover the pot, set a timer, and poach for 17 minutes for a runnier yolk and 20 minutes for a creamier yolk.
- My hot water temperature gradually declined to 154–158°F (68–70°C).
- Remove from the water: Open the lid, remove the eggs from the hot water, and set aside for 5 minutes. The residual heat will continue to cook the eggs.
- The water temperature was 154°F (68°C) when I opened the lid after 20 minutes.
- Ready to serve: Serve warm or at room temperature with a drizzle of the dashi soy sauce or add one to curry rice, noodle soup, a hambagu meal, a rice bowl, or a plate of cold noodles.
FAQs
What if I don’t have a heavy-bottomed pot?
A lightweight or thin-bottomed pot is usually made with materials that may heat up and cool down more quickly than heavy-bottomed pots. Therefore, try using less cold tap water, about ⅓–½ cup (100–150 ml) instead ¾ cup (200 ml). If you try this method, keep us posted on your results in the comments below.
Can I use medium eggs?
Since they are smaller, they will cook faster. Please shorten the cooking time. FYI, a large egg without the shell is 50 grams.
How to Serve Onsen Tamago
Onsen tamago with a dashi-based soy sauce (だし醤油) is a typical choice of egg to serve for Japanese breakfast.
You can also serve onsen tamago in various dishes. I adjust the onsen tamago’s cooking time to cook the egg yolk more or less depending on how I use it. For example, I prefer a runny yolk on Japanese curry and a firmer yolk on hambagu.
Here are some of my suggestions:
- Put it over fried rice: Kimchi Fried Rice, Garlic Fried Rice
- Top your Japanese curry rice: Japanese Dry Curry, Keema Curry, Chicken Curry, Vegetarian Curry, Beef Curry
- Add it to a rice bowl: Gyudon, Yakiniku Don, Tamago Kake Gohan
- Put it in noodle soup: Kake Udon, Cold Tanuki Udon, Vegetarian Udon, Soba Noodle Soup, Miso Ramen, Vegetarian Ramen, Shoyu Ramen, Mazesoba (brothless ramen)
- Top a main dish: Hambagu (Japanese hamburger steak), Nikomi Hambagu (stewed hamburger steak), Loco Moco, spaghetti carbonara (my favorite), Avocado Toast
- Put it in your soup and hot pot: Classic Miso Soup, Cabbage and Onsen Tamago Miso Soup, Cold Miso Soup (Hiyajiru), Zosui (Japanese rice soup), Nabeyaki Udon, Miso Nikomi Udon
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Onsen Tamago (Japanese Hot Spring Egg)
Video
Ingredients
- 4¼ cups water (1 L)
- 4 large eggs (50 g each w/o shell) (refrigerated)
- ¾ cup tap water (200 ml; colder than room temperature)
For the Sauce
- ¼ cup dashi (Japanese soup stock) (4 Tbsp; use standard Awase Dashi, dashi packet or powder, or Vegan Dashi)
- ½ Tbsp mirin
- 1½ Tbsp soy sauce
- 2 Tbsp katsuobushi (dried bonito flakes) (skip for vegetarian)
For the Garnish
- green onion/scallion
Instructions
- Before You Start: You must use a small, heavy-bottomed saucepan (I use All-Clad Copper Core 2 QT saucepan) that retains heat well and is small enough to completely submerge the eggs in the measured water. If you don‘t have one, please see my FAQs section of the blog post for my suggestion. Also, you need exactly 4 refrigerated large eggs for this recipe to achieve the correct water temperature for poaching. Now, gather all the ingredients.
To Poach the Eggs
- To the heavy-bottomed saucepan, add 4¼ cups water (1 L). Cover with a tight-fitting lid and bring it to a boil.
- Once boiling, turn off the heat and remove the pot from the stove. I moved my saucepan to a hot pad on my countertop. Next, remove 4 large eggs (50 g each w/o shell) from the refrigerator.
- To the pot of just-boiled water, add ¾ cup tap water (200 ml) that's colder than room temperature and stir. The hot water in the saucepan should be roughly 180°F (82°C). Then, gently submerge the cold eggs, one at a time, into the hot water using a fine-mesh skimmer. Tip: If you‘re using a lightweight or thin-bottomed pot, try adding only ⅓–½ cup (100–150 ml) of cold tap water instead.
- Immediately cover with the lid and set a timer for 17–20 minutes. Poach 17 minutes for runnier yolks and 20 minutes for creamier yolks. If you follow my method precisely, the water temperature will be 154°F (68°C) when you open the lid after 20 minutes. Note: If you prefer a firmer yolk, you can experiment with a longer poaching time.
To Make the Sauce
- Meanwhile, make the sauce. Combine ¼ cup dashi (Japanese soup stock), ½ Tbsp mirin, 1½ Tbsp soy sauce, and 2 Tbsp katsuobushi (dried bonito flakes) in a small saucepan and bring it to a boil.
- Once boiling, turn off the heat.
- Strain through a sieve and set the sauce aside.
To Finish the Onsen Tamago
- After 17–20 minutes, gently take the eggs out of the water, one at a time. Set them aside for 5 minutes. The residual heat will continue to cook the eggs.
- Meanwhile, cut the green onion/scallion into thin slices and set aside.
To Serve
- Enjoy the Onsen Tamago either warm or at room temperature. Crack the egg into a small bowl, pour the dashi-based sauce into the bowl, and garnish with the sliced green onion as a part of a Japanese breakfast. Try the egg on top of steamed rice with a splash of soy sauce. It’s also delicious in a rice bowl, on top of Japanese curry rice, in hot noodle soup, or on a plate of cold udon or ramen noodles. See below for serving ideas.
To Serve Onsen Tamago in Other Dishes
- Top a rice dish: Onsen Tamago is a protein-rich topping for fried rice like Kimchi Fried Rice and Garlic Fried Rice. Try adding one to finish a Japanese curry rice plate like Japanese Dry Curry, Keema Curry, Chicken Curry, Vegetarian Curry, and Beef Curry.
- Add it to a rice bowl: It‘s a silky and rich topping for Gyudon (simmered beef bowl) and Yakiniku Don (grilled beef bowl). It also works beautifully in a poached-egg version of Tamago Kake Gohan.
- Put it in noodle soup: Up the protein and add one to your Kake Udon (classic udon noodle soup), Vegetarian Udon, Cold Tanuki Udon, and classic Soba Noodle Soup. It‘s also great in Shio Ramen, Miso Ramen, Vegetarian Ramen, Shoyu Ramen, and Mazesoba (Japanese brothless ramen).
- Top a main dish: Add one to your Hambagu (Japanese hamburger steak), Nikomi Hambagu (stewed hamburger steak), Loco Moco, and spaghetti carbonara (my favorite). It also works well on Avocado Toast.
- Put it in your soup and hot pot: Bulk up your Japanese soups by adding one to classic Miso Soup, Cabbage and Onsen Tamago Miso Soup, Cold Miso Soup (Hiyajiru), and Zosui (Japanese rice soup). It‘s delicious in Nabeyaki Udon, Miso Nikomi Udon, and Hot Pot for One, too.
To Store
- You can keep the uncracked Onsen Tamago for 1–2 days in the refrigerator. To reheat, remove it from the refrigerator and bring it to room temperature. To warm it up further, place it in a bowl of 160ºF (70ºC) water for 10 minutes. Do not reheat higher than that; otherwise, the heat will cook the egg. Keep any leftover sauce in the refrigerator for 4–5 days.
Nutrition
Editor’s Note: This post was originally published on January 22, 2015. It was republished with a new video, new images, and more helpful content on April 19, 2024.
For those of you who live at a high altitude (my home ~6,200ft), I tended to get the best results with 21 minutes
Hi O. Cornali, Thank you so much for trying Nami’s recipe and sharing your experience with us.
This helps other readers who live at high altitudes. Thank you very much!
[…] Onsen Tamago (Hot Spring Eggs) | Easy Japanese Recipes at http://www.justonecookbo… […]
Hi Nami, how are you? I was really looking forward to have Onsen Tamago for our Sunday breakfast, but I made the mistake of not watching the video before, so after submerging the eggs in the water pot, I put it back on the stove and let it simmer for 17 minutes …!!! The result, of course, is hard boiled eggs as solid as rocks, which really made me laugh, but I will use for some other dish …
I will try again soon, hopefully next time I will succeed!!!
Hi Rolanda! Oh no!!! 😀 Hard boiled eggs take 10 minutes or so, so 17 minutes is… overcooked. 😀 Hopefully next one will be a successful one! Thank you for making me smile. Trust me I have a lot of mistakes along the way… 😉
Tried again tonight and I am getting there, even if I think that I need to adjust the timing because of the altitude, which affects the temperature of boiling water. Anyway the sauce is delicious and the egg is fantastic on white rice.
Thanks so much for trying this again! I can’t imagine dealing with the altitude when cooking/baking. Cooking/baking itself is already hard sometimes and to take the altitude into consideration… I would go nuts. Kudos to you!
[…] Onsen Tamago (Hot Spring Eggs) | Easy Japanese Recipes at http://www.justonecookbo… […]
[…] Onsen Tamago (Hot Spring Eggs) | Einfache japanische Rezepte an http://www.justonecookbo … […]
Why do your directions say to “set timer for 17 minutes (or longer)?”
When / Why would we need a longer time?
Hi Casey! In my cooking condition, 17 minute of cooking is perfect for my liking. Some people may think it’s too runny hence I wrote “17 minutes (or longer)”. It should not be less than 17 minutes. Maybe it’s confusing to write “(or longer)” so I’ll delete this part.
Hi Nami! I was super excited to try this recipe, but as a few others have reported, mine came out extreamly underdone – I had almost completely clear egg whites! I’m going to experiment with three eggs instead of four and might try adding less cold water before setting them aside to “cook”. I look forward to reporting back with better results 🙂
Hi Brittany! Sorry to hear that yours came out undone. Considering both of our eggs are in the fridge (similar temp), only difference between mine and yours is the room temperature, the heat on stovetop, tap water temperature, and the saucepan (how well you can retain the heat. My saucepan is a stainless steel one and it retains heat pretty well. Was yours thin?). You may need to adjust the amount of water you add… Hope it’ll work next time. 🙂
Hi Nami, Thank you for your wonderful recipe. Tried numerous recipes and your recipe works the best. My kids loved it. The last time I tried it I had the refrigerated eggs taken out of the fridge (700g) when I put the pot of water to boil – That seems to get a better result. I am also wondering how do I adjust the timing so I get the whole egg white out without the liquidy egg white at the sides. Is it important to leave it to rest for the 5minutes when you take it out from the pot? I know you are busy. Hopefully you will have the chance to do the two eggs recipe or using thermal container Thanks!!
Hi Mandy! How about cooking slightly longer to avoid the liquidy egg white? I think it might help. 5 minute is to cook the egg with residual heat. You can experiment with different timing but don’t soak in cold water etc. It will not be enough cooking time, unless you increase the cooking time. Yeah one day I’ll try 2 eggs. Thermal container, maybe. Each brand of thermal container works differently too, so it’s hard to control the heat, I think. 🙂
Thanks!
Thank you Henry! 🙂
Hi! I just tried this with four eggs and it’s perfect!!! I don’t know how you come up with such an amazing fail proof recipe.
If I want more than four eggs, do I adjust the amount of water accordingly? Does it work that way?
Hi Joanne! You and I probably use similar equipment and that’s why our outcome was similar. 🙂 I’m sore some people over/undercook because their pot doesn’t sustain the same amount of heat etc… 🙂
No, unfortunately…. you can spend many eggs to figure out if you always make more than 4 eggs. I developed this recipe as 4 seems good number for majority of readers… 🙂
hi nami… perfect recipe ..
although i like the tight eggs … i will try it …
… one question .. how to boil the egg at a lower temperature and be safe….?
(sorry for my english… is not very good)..
Best wishes….
Hi Chris! Maybe this article may help.
Hope this guideline will help: https://eggsafety.org/cooking-eggs-right-temperature/
These are great directions! I loved this for breakfast, like a little shot of protein. I love eggs, and enjoy your other egg recipes but this is the tastiest!
Aww thanks so much for your kind feedback and compliment. 🙂 I’m glad you enjoyed the recipes. xo
I just wanted to put some info down and see if anyone has information for my issue with this recipe (it’s actually a problem with almost any egg recipe where they are cooked inside the shell):
I live in a pretty high altitude and I think this is affecting the eggs. Even at more than 25 min in, the white were raw and runny (at 25 min was when the water started to noticeably cool so I didn’t try past this). The last egg had started to turn white, but clearly was far too undercooked.
I would love to make this recipe, but I’m not sure if I should even add cold tap water at all in this case. I have a pretty good idea of how long to cook both hard and soft boiled eggs, but it took years of asking others who live near me and playing around with temps to get it to work. Any suggestions would be helpful as I’m almost a dozen eggs into trying this (at 4 eggs each time) and I’m not even close.
Hi Kat! I quickly researched in Japanese and I found some article… have you tried cooking for 5 minutes at 85C (boiling)? This person said he made a perfect Onsen Tamago
at 4000 m (http://www.geocities.jp/esashi_ume/Setuzoku/Peru8.htm).
This is Japanese but it’s interesting to figure out how long it takes to make a boiled egg.
https://www.data-artist.com/atelier/20150718.html
Use google chrome to translate to English?
Thanks Nami! I really like that Japanese site (it’s certainly fun to watch the egg cook and I have some knowledge of Japanese so although I couldn’t understand everything, I was able to read some of it). I have found to cook soft boiled eggs here it takes around 7 min (it’s a little less than that) from fridge temp eggs in boiling water.
For this recipe though, would you suggest not adding any cold water to the boiling? I think that might be why they are so undercooked (our water isn’t icy cold). I was trying to get these to soft boiled consistency, but as I noted, even at 25 min, only the barest sliver of white had started turned from clear. I also noticed this: the boiling water reduces temperature rather quickly. I’m on the foothills in Colorado (so we’re pretty high up), which means our water will boil at a much lower temp than other places. Any suggestions for how to cook these eggs? I have a few types of thermometers for cooking (a candy one, a digital meat one, etc), so if you could give me a general temp your water is at after you’ve add the cold water, I can start with that. Thanks again!
Hi Kat! Forgot to answer your question about that water. Yeah I agree. I think you might want to try without adding water. Then if the temperature is too high, you might need to adjust with the water… You must be eating lots of eggs these days. 🙁 Hope you’ll find out the best solution for your Onsen tamago soon! xo
Thank! Okay so here’s my results starting from boiling (my water only hits about 82 degrees C at full rolling boil) and after 25 min, the water had still cooled too far for the eggs to cook (the ending temp of the water after 25 min was only 59C). So I’m getting the feeling that I’m going to have to try to keep the water at a fairly consistent temp. I’m guessing just trying to soft boil them is all I’ll be able to pull off by the looks of how cool the water is here. Is that what your assessment would be too?
Hi Kat! If only 59C, egg yolk won’t become solidified (need to be 70 °C) and egg whites will be impossible to solidified (need 80 °C). Your eggs will be not cooked… 🙁 Sorry… I can’t imagine how hard it must be to cook at high altitude.
Hi, Nami. I just tried making onsen tamago following your recipe this morning. Unfortunately, even though I followed the recipe exactly, the eggs did not turn out right. The whites were very runny and the yolks overcooked to a point that they became custardy. What do you think could have caused this to happen? Thank you.
Hi Veronica! Hmm hard to tell what went wrong or what could cause your result. As this method doesn’t use a thermometer, tools, eggs, and water temperature makes a difference. A type of pot (how heat transmit to egg) and the number of eggs are very important factor. I had to test with several eggs to find out the timing with my pot and eggs, but it may be different from yours. I recommend using the same method (pots, egg, water) to find your time, and then keep using the same approach. Hope this makes sense.
Absolutely delicious! 😀 Ended up eating three in a row when they were done.
(Baaad idea; eggs is still eggs!) I recommend eating only one at a time, no matter how tempting they may look.
Hi Liz! Haha 3 in a row! 😀 But I can’t laugh as I probably ate more when I was testing this recipe for the perfect cooking time… What else could I do… I didn’t want to throw away food…. xD
IF using refrigerated eggs, wouldnt the eggs crack upon contact with hot water?
Hi Zac! No, it won’t. I always use this method and I don’t have any issue. But make sure you don’t “drop” the eggs into the water. You have to gently submerge them…. 🙂
Thanks for the reply Nami. I tried it, it didn’t crack! Which is strange because when I did soft boil eggs, it cracked due to thermal shock. Anyway I tried this recipe but eggs were undercooked, still transparent. I’ll adjust accordingly. I also tried the ramen egg recipe and it worked! Except for 1 smaller egg which is more cooked due to its size haha.
Hi Zac! This recipe (without using thermometer) works perfectly when we have exactly same products and condition…. which is kind of hard to achieve. We got to use same pot (each one conduct heat differently) etc. So please test the cooking time. I had to test several eggs to figure out cooking time for me. But once you know, just use same pot and it should work every time. 🙂