Onsen Tamago literally means ‘hot spring eggs’ in Japanese. It refers to eggs that were originally prepared in hot spring water to create silky egg whites and custard-like yolk. Here’s how you can make this delicious egg recipe at home.
In the past, I’ve shared some popular Japanese egg recipes on Just One Cookbook such as Omurice, Tamagoyaki, and Ramen Egg (Ajitsuke Tamago). Today I’ll add another popular dish to the egg recipe collection, and it’s Onsen Tamago (温泉卵).
Watch How To Make Onsen Tamago
Originally prepared in hot spring water in Japan, this delicious egg recipe with soft silk egg whites and custard-like yolk is easy to make at home.
What’s Onsen Tamago?
Onsen means hot springs, and tamago means eggs in Japanese. Why is the name “hot springs eggs”? Originally, eggs that were prepared this way were slow-cooked in Japan’s warm hot springs water.
What’s so special about these eggs? These eggs are perfectly poached inside its shell. While the whites are soft and silky, the yolk comes out firm but retains the color and creamy texture of an uncooked yolk. It’s basically the complete opposite of soft boiled eggs that are firm whites and soft egg yolk.
The Chemistry Behind Onsen Tamago
This special texture is achieved because egg yolk and egg white solidify at different temperatures. Egg yolks solidify at 158 degrees °F (70 °C) and egg whites solidify at 176 degrees °F (80 °C). Therefore, if we maintain the cooking water to be at 149-154 degrees °F (65-68 °C), we’ll get a perfect spherical poached egg, creamy and silky on the outside and firm on the inside.
This Recipe Works for EVERYONE.
There are many ways to make the perfect onsen tamago, but this technique does not require a microwave, a thermometer, or any special cooking gadget.
Here are the highlights of this technique:
- Requires just a stove and pot (which I hope everyone has in their kitchen).
- Does NOT require a thermometer.
- Use refrigerated eggs. Some recipes require eggs to be “room temperature”, but the “room” temperature could be different depends on where you live.
- Not required to soak eggs in iced water after cooking, in case you don’t have ice cubes handy.
If you follow my recipe precisely, you should be able to achieve perfect onsen tamago as the final result. The only requirement is to use 4 large eggs. If you use different size eggs or reduce/increase the number of eggs, it will not work as the water temperature will change.
How Do you Enjoy Onsen Tamago?
You can enjoy onsen tamago with a dashi-based soy sauce (だし醤油) which is usually served as a part of Japanese breakfast. Also, you can place it on top of the steamed rice, splash some soy sauce over, mix and enjoy; serve with gyudon, curry rice, soba noodle soup, and cold udon; or even mix with carbonara (my favorite!).
Now let’s get started! The best part about this recipe is you do not need to visit hot springs in Japan to enjoy these special eggs. Make the perfect onsen tamago right at home!
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 degrees °F (74 °C) in order to be considered safe. The perfect temperature for cooking onsen tamago is 149-154 degrees °F (65-68 °C), which is below the guideline. There is a risk of salmonella with consuming undercooked eggs.
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Onsen Tamago
Video
Ingredients
- 4 ¼ cups water (measure 4 ¼ cups and remove 4 tsp to be precise)
- ¾ cup tap water (¾ cup + 4 tsp to be precise; needs to be colder than room temp)
- 4 large eggs (50 g each w/o shell) (refrigerated)
Sauce
- ¼ cup dashi (Japanese soup stock; click to learn more) (4 Tbsp; use kombu dashi for vegetarian)
- ½ Tbsp mirin
- 1 ½ Tbsp soy sauce
- ⅓ cup katsuobushi (dried bonito flakes) (skip for vegetarian)
- green onion/scallion (for garnish)
Instructions
- Gather all the ingredients. You will need a small heavy-bottomed saucepan (I use 1.5 QT); the water should cover the eggs with 1000 ml water completely.
- Add 1000 ml water in the saucepan, cover with a tight-fitting lid, and bring it to a boil.
- Once boiling, remove the pot from the heat. Take the eggs out from the refrigerator. Add 200 ml cold tap water and gently submerge the cold eggs in the hot water. Immediately cover and set the timer for 17 minutes.
- If you like to enjoy onsen tamgo with the sauce, combine the dashi, mirin, and soy sauce in a small saucepan and bring it to a boil. Add katsuobushi and turn off the heat, let katsuobushi sink at the bottom of the pan. After 30 seconds or so, strain through the strainer and set the sauce aside. You can keep the sauce in the refrigerator for 4-5 days.
- Cut scallion into thinly slices and set aside.
- Once 17 minutes have passed, take the eggs out gently and set aside for 5 minutes.
- You can enjoy onsen tamago either cold or warm. Crack the egg and pour the sauce over, garnish with chopped scallion.
To Store
- You can keep the uncracked onsen tamago for 1-2 days in the refrigerator. To reheat, take out the onsen tamago from the fridge to room temperature. Place it in 160ºF(70ºC) water for 10 minutes to warm up. Do not reheat higher than that otherwise the egg will be cooked.
