Onsen Tamago: Japanese Soft Boiled Egg Recipe

If you have a chance to take a trip to a

hot spring resort in Japan, you may see hen’s shell eggs placed under the spring water.

Onsen Tamago (温泉卵)

Those eggs are called “Onsen Tamago (温泉卵)”. They are usually put in a mesh basket and cooked using the middle/high-temperature water of the Onsen.

Onsen Tamago

With hen’s shell eggs submerged in hot water between 65 to 68 ℃ (149 to 154.4 degrees Fahrenheit) for 30 minutes or so, they become soft-boiled eggs whose white is softer than the egg yolk.

The egg white is softly set, while the egg yolk has a custardy texture because the former’s solidifying temperature (about 70 ℃: 158 °F) is lower than that of the latter (about 80 ℃: 176 °F).

How to Make (Easy Recipe)

Onsen Tamago Soft Boiled Egg

Using the properties of the egg, you can easily make Onsen Tamago at home.

Today, I actually made it following the directions of the popular recipe on Cookpad.com. And here, I will share the cooking process with photos for those interested.


All you need to prepare for this recipe are listed below.

  1. Large hen’s shell egg: 1 – 4 eggs
  2. Water: 1000 cc
  3. Additional cold water: 400 cc
  4. Kikkoman’s Hon Tsuyu soup base: 1 teaspoon
  5. Shiro Dashi soup base: 1 teaspoon
  6. Mirin sweet cooking rice wine: 1 teaspoon
  7. Water for the sauce: 3 tablespoons

As preparation, make the sauce for the egg beforehand; mix the No.4 to No.7 ingredients together in a small bowl. Now, let’s get the cooking started.


1 First, put 1000 cc of water in a pot and bring it to a boil.
2 Once the water has boiled, turn off the heat and add 400 cc cold water.
3 Put the hen’s shell egg into the water gently with a ladle.
4 Then, cover up the pot with a lid and let the egg immerse in the water for 25 minutes or so.
5 After that, take the boiled egg out of the pot. Then, transfer the egg into a bowl of cold water and let it cool down for a while.
6 Break the shell and slip the contents into the prepared sauce. Enjoy Onsen Tamago!

(Reference Page: Wikipedia 温泉卵 )


Hi, I'm Tomo, a Japanese blogger living in Niigata Prefecture, Japan. For the purpose of enriching your life, I would like to introduce things about Japan on this blog, especially unique Japanese products, cooking recipes, cultures, and facts and trivia.

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