Onsen Tomago (Japanese soft boiled eggs)

Onsen Tomago is a must-have breakfast food in Japan.  You can mix it with rice, dip other foods like fish into it, or eat it straight out of the shell.  They also make a great pasta topper.

Onsen Tomago comes from two Japanese words –  An Onsen is a Japanese hot spring, and tomago is the word for an egg.  If you have ever sat in a Japanese hot tub, sometimes it seems like the water is hot enough to cook an egg, and there are indeed hot springs in Japan heated by volcanic springs where that may be possible.  But wherever the name came from, Japanese soft boiled eggs are a staple for Japanese breakfasts and very easy to make as long as you do it correctly.

Don’t strap on the feedback immediately though- these eggs take at least 30 minutes to prepare.  You can’t boil an egg for a few minutes to make a proper onsen tomago- it requires soaking in hot water and then allowing it to cool.  They are usually served cold or at room temperature and used to top other dishes although they can be eaten out of the shell.

The perfect onsen tomago has an egg white that is cooked lightly until it is white but still soft.  The yolk is soft and holds together until pierced. When cracked, the entire egg will roll out of the shell and can be poured directly into a bowl or over rice or pasta as desired.

I have been enjoying these for many years. They are a good alternative to raw eggs because they are cooked through, and they can be used to to top off carbonara or rice dishes like bibimbap.  You can also use these as a topper to a Caesar Salad.

Like any other soft boiled egg, the preparation involves cooking them in hot water.  When cooking these, the most important thing to remember is not to allow them to touch each other while they are soaking.  The shell needs to be completely surrounded by hot water to ensure that they cook through evenly.  It also helps to allow refrigerated eggs to warm to room temperature before immersing them in hot water.

Try out this simple recipe and let us know what you think!

Onsen Tamago (Japanese soft boiled eggs)

Onsen tamago is easy to make and you can cook them in quantity and refrigerate them for later.  They go perfectly with white rice and are quire good on their own.  You can also use them in pasta carbonara, Caesar salads, and over noodles to provide a creamy and eggy flavor to these dishes.

30 minutes 4 eggs
PREP 30 minutes
YIELD 4 eggs


  • Four medium eggs (at room temperature)


  • Bring a pot of unsalted water to a rolling boil (make sure the water is deep enough to completely submerge the eggs).

  • Remove the pot from the hot burner and let the water sit for 1 minute.  Gently place the eggs in the pot so they are not touching each other.

  • Let the eggs sit in the water for 12 minutes.  Do not touch them or move them while they are sitting.

  • Using tongs or a spoon, gently place green eggs in a bath of ice cold water.  Let them sit for at least 15 minutes to completely cool them through.

  • The eggs are now ready to serve or refrigerate.

  • Serve the eggs.  Crack over white rice.  Add salmon flakes or tsukemono.
Onsen tamago over white rice with soy sauce and pickled Napa tsukemono
Onsen tamago with salmon flakes


  • If you are not in a hurry you can skip the ice bath and leave the eggs submerged in the same water for at least 3 1/2 hours to completely cool to room temperature.
  • Unused eggs can be refrigerated for 5 days.


Related Recipes

Leave a Reply