Onsen Tamago: Japanese Soft Boiled Egg Recipe

If you have a chance to go on a hot spring trip in Japan, you may see hen’s shell eggs placed under the hot spring water in the Onsen resort you visit.

Onsen Tamago (温泉卵)

Those eggs, literally called “Onsen Tamago (温泉卵)”, are usually put in a mesh basket and cooked through by the use of the middle/high temperature of the natural hot spring.

Onsen Tamago

When you leave 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.

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

How to Make (Easy Recipe)

Onsen Tamago Soft Boiled Egg

Using the properties, you can easily make the hot spring soft boiled eggs “Onsen Tamago” at home. Today I actually made an Onsen Tamago egg according to this popular easy-to-make Onsen Tamago recipe on Cookpad.com.

So for those of you who are interested in the Japanese-style soft boiled egg recipe, here I will share the instructions with photos.

Ingredients and Preparation

All you need to prepare for this Onsen Tamago 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 Onsen Tamago egg beforehand; simply mix the No.4 to No.7 ingredients together well in a small bowl. Now, let’s get the cooking started.


1 First, put 1000 cc of water in a pot and bring to the boil
2 Once the water has boiled, turn off the heat and add an additional 400 cc of 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 sit and cook for 25 minutes or so
5 About 25 minutes later, take the boiled egg out from 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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