10 January 2010

Onsen Tamago - Hot Spring Eggs

I stumbled upon this recipe when I was googling around for something completely different. Well.. probably not totally different, or else google wouldn't have returned this as part of its search results .. albeit way down in about the 4th page of results.

By the way, I was searching for silky tofu japanese recipes. And one of the returns was a recipe for Onsen Tamago.. at home. I've had this before when I was travelling around in Japan. So the thought of being able to reproduce this as home got me interested.

To put it simply, Onsen Tamago is an egg disk that is commonly served as a breakfast item at the accommodations around the hot springs in Japan. The reason being that the temperatures of the hot springs are perfect for poaching these eggs over a long period of time. The resulting egg is so delicate and silky that it just slides down your throat. The eggs are poached inside it's shells until the yolks are set on the outside, but the whites are still only loosely set and creamy.

Which.. if you explore the physics of eggs, I remember reading somewhere that egg white begins to set at 63C, while egg yolk begins to set at 65C. Which means that the egg had to be poached at about 64C constantly so that the whites so not completely set and go hard. Afterall, I'm not looking to make a hard boiled egg here.

Quite the opposite.. Think Joël Robuchon's Egg Cocotte. But a more simplified.. Asian version.

So.. back to the recipe. The amusing part about this was that you use a rice cooker to simulate the cooking phase from the hot springs. Apparently, when the rice has finished cooking, the rice cooker will automatically switch to the handy ‘keep warm’ setting – which coincidentally maintains the a similar temperature for making onsen tamago. All you need to do then is wrap the egg in a layer of kitchen paper (this is just to make sure the eggs aren’t heated directly) and set it gently on top of the cooked rice. Cover, and leave to ‘cook’ for one hour.

onsen tamago

Onsen Tamago - Hot Spring Eggs
Recipe adapted fromTastyTreats - Serves 4
  • 4 eggs
  • Kitchen paper
  • 1 sprig spring onion (finely sliced)
  • couple of coriander leaves
Dashi Broth:
  • 1/2 cup of hot water
  • 1 tablespoon of dashi broth granules
  • 1 tablespoon Mirin
  • 1 1/2 tablespoon light soy sauce
  1. Dissolved the dashi broth granules in 1/2 cup of hot water, add in mirin and light soy sauce. Mix until its all combined together and leave to chill in the fridge until needed.
  2. For the Eggs: Run them under warm water if you take them straight out of the fridge and want to use immediately. With a rice cooker that’s just finished cooking some rice and is on the 'keep warm' setting, get some kitchen paper and wrap each egg individually.
  3. Place into the rice cooker to cook for 45mins.
  4. When time’s up, gently crack your egg open and let it slide into the dashi mixture you’ve made in advance. Sprinkle over some chopped spring onions and coriander leaves.

onsen tamago2

I put a piece of steamed tofu into each of the dashi broth bowls as well. Remember..? I was originally looking for a silken tofu recipe so I can use up my tofu somehow. Given the similar texture, they actually worked pretty well together in the dashi broth. :)


  1. What a lovely recipe! I made the broth a little stronger with more soy, mirin and dashi in the same amount of water...I also added some white pepper and the coriander and onion to the broth...as I will let the eggs 'pickle' in it for a few days...ready for the lunch box!! Thankyou :-)

    1. Hi Jane,

      i've never actually let the eggs pickle for a few days like this b4.. did it work ?

      I have tried soemthing else similar with semi-hard boiled eggs though. very tasty !


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