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!
When you crack the egg, how do you make sure it comes out ‘intact’? You cant peel it for obvious reasons since the white is still runny. Thanks.
Hi Al! If you crack the eggs like how you normally crack, you won’t damage the onsen tamago and it won’t break easily unless you poke it etc. 🙂
SImple and easy, thanks.
Thank you for checking my recipe! 🙂
I screwed up the first time I missed out on step 2.
Hi Bill! Oh! You forgot to add water? 😀
My Onsen tamago turned out perfect! Thank you!
Hi Angela! I’m so happy to hear that! Thank you for letting me know! 🙂
Hi Nami! I tried making these eggs as a core component of ontama udon, but it seems like I failed to get it cooked enough 🙁
From what I understand it’s also common to eat the egg raw and I didn’t mind it and went ahead and ate it, but it was less cooked than pictured and intended. Some of the whites were still transparent and more runny. Any advice on what I might be doing wrong/how I can improve it?
Thanks!
Hi Lyanne! I created this recipe so that it’s not required my readers to use a kitchen thermometer (not everyone has it), you have to follow the recipe exactly. The number of eggs, water amount, everything matters to create the perfect water temperature to cook the eggs.
Having said that, the only difference between mine and yours is our pots. Mine could be more insulated if yours didn’t cooked enough. Maybe your pot might escape the heat more, or your kitchen can be colder than my kitchen. That could be the only difference, as refrigerated eggs and running water from faucet should be pretty similar temperature. If you follow the recipe exactly and ended up with less cooked eggs, you could:
1) cook for a longer time
2) add less water
which will help cook the eggs. But then you’ll have to measure the cooking time etc and experiment… I spent some time making this recipe testing time and temperature (lots of eggs used for testing recipes!)… I really hoped that people didn’t have to go through all that troubles…
Sorry yours are undercooked. Hope you can figure out the perfect temp or time to cook your eggs. 🙂
Hi Nami:
I attempted making onsen tamago using your recipe and wow so so lovely. Thank you!
By the way, while searching for something online I came upon this gadget, a yellow half-boiled egg cooker from Malaysia (http://bit.ly/2cdnwZT). It is written that local coffee shops still use them. I’d love to hear what you or other readers know about it. I do question the use of plastic though. Also not sure about another one-purpose gadget for the kitchen.
Hi Christina! I’m so happy yours came out well! I’ve never used or heard of this gadget until you mentioned. I know Instant Pot (pressure cooker) makes great eggs too, which has multi functions… so I’d highly recommend that instead of this one. 😀 Though, Instant Pot is American size and too big for some kitchen (like Japanese kitchen…).
If I am doubling the recipe, do I wait longer than 17 minutes?
Hi Mary! Unfortunately it doesn’t work like that. I made this recipe, specifically for people who don’t have thermometer. It’s very precise when it comes to the water temperature and cooking time. So if you add more eggs, the water temp will drop drastically, and even you cook for a longer time, the result will not be the same. So for this recipe, it only works if you follow the recipe (and use a similar thickness of pot – so heat won’t escape much). 🙂
I tried making this today and followed the recipe exactly but the eggs were so runny still the whites had near no firmness and were mostly goo, the photos looked like it was solid enough to hold its shape . I’ll probably try it again without the cold water. All your recipes look so yummy. I bookmarked many to save. Thaks for sharin .
Hi Crystal! Only difference between my eggs and your eggs are….
– different pot and lid
– different egg size (even though it can be both “large”).
tap water temp and refrigerator temp should be pretty much same. Different pots/lid transfer heat differently, and maybe yours escape heat faster hence colder water to cook eggs.
If you’re going to use the same pot, cook longer, or reduce the amount of water etc to bring up the temp or simply cook longer. I did a few experiment to make sure the outcome is good, but we all have different pots, so that can be tricky…
I’m happy to hear you find some recipes you want to try from my blog. Hope you enjoy them! 🙂
I did my first attempt with just 2 eggs in a smaller pan (holds about 800ml) so the eggs would stil be covered completely by the water. I used 600ml of water to heat up and 120ml of tap water to cool down. Took out the first egg at 17min, the yolk was still partially runny. Took out the second egg at 18min and the yolk on that one had a very even consitency. The whites were still quite fluid though (is this as it’s supposed to be?) – will try 19min on the next run and see how that turns out. But all in all turned out very nicely for my first attempt, thanks for the recipe 🙂
Hi Raphael! Thank you so much for sharing! A lot of readers want to make 2 eggs, so your input will help many JOC readers! Thanks again!
Hi, Nami!
I’ ve tried the egss this morning but they turned out hard boiled eggs :(. Mayb i used small to medium eggs instead of large one, so mayb i should reduce the time from 17 mins to 15 mins or shorter? If i only cook two eggs, should i reduce time as well? Thx for your time! 🙂
Hi Nina! Thank you for trying this recipe! As I mentioned, this recipe only works with 4 eggs. 2 additional cold eggs that you didn’t add supposed to lower the temperature of the boiling water. The size also matters but you can easily reduce the cooking time. We use different pot, so you might need to adjust the cooking time and require some “practice run” before you get the perfect onsen tamago. 🙂
Hello
I’m planning to make onsen tamago this Sunday, but I need 5 eggs (as there are 5 people). In your recipie you state that this only works with 4 eggs. Do you have an idea how I could make it work for 5 eggs.
Ronja
Hi Ronja! The weakness of this recipe is that we can’t change the number of eggs. When you add 5 eggs, the temperature of the hot water will decrease more. I haven’t tested recipe with 5 eggs, so I don’t know how long the eggs will take to cook perfectly. Sorry… I usually keep the egg for next day when I make extra. 🙂
Hi Namiko,
I love your recipes, it has been a life saver since I moved to Japan!
I tried to make onsen tamago but the egg cane out totally raw. It’s 2 degrees now, and the tap water is icy cold and that could have been the reason. Could you advise what I can do with water of such temperatures for adding to the boiling water?
Thank you!
Chloe
Hi Chloe! I hope you’re enjoying your life in Japan! 🙂 Ah I just remembered how cold tap water was in winter (I’m used to California tap water temp now). I totally agree – that could be the reason. Your cold water was more like iced water…. 🙂 Reduce the amount next time – you have to experiment a little bit. Cut down to half to see how it works next time?
What temperature is your tap water then? I’d rather use a thermometer than dump a completely raw egg into my bowl again 🙁 The entire thing was a cloudy liquid mess.
Hi Alanna,
Thank you for bringing this to our attention.
Nami will share the Onsen Tamago recipe using a thermometer one day. She knows most cooks don’t have kitchen thermometers, so she created this recipe without using one. Many people have succeeded so far, but some people may need to adjust as we all use different tap water temperatures, different stoves, pots, etc., and heat will conduct differently. We are sorry that this recipe didn’t work for you.😔
This is a great recipe! I had to leave the eggs in the water for 22mins but it was awesome. Love the texture of the egg! Thanks for sharing!
Hi Jannica! I’m glad to hear you figure out the time that works for you! From now on, you know how to make perfect onsen tamago every time if you use the same pot, etc. 🙂 Thank you so much for trying my recipe!
Followed step by step but started to removed eggs from covered pot at 1min intervals (at 15mins) and found the best two to be 16-17min mark.
Thanks for sharing this Nami.
That’s exactly what I did too! I’m glad you found the cooking time for your perfect onsen tamago! Thank you for trying my recipe! 🙂
Hi Nami! thank you for this incredibly easy to follow way to create onsen-tamago. I used to make them in thermos jars with a thermometer constantly on standby, this is much much easier. I love your other recipes too, thank you for all you do 🙂
Hi Carol! I’m happy to hear you like this recipe! I get a lot of feedback from readers and I wanted to make a recipe that everyone can make using only things most people have… 😀 Thank you so much for reading my blog!
Woah. these eggs came out just great! I searched for the ramen recipe on your site but there’s none. Since I don’t want to screw up another time with it, I thought your version would be the most balanced. Yeah.. so that’s a hure request from me! Show us some nice ramen c:
Hi Keith! I’m happy to hear you liked the recipe! I have two ramen recipes and chashu recipes on my site. Search ramen and it should come up. 🙂