These aren’t ordinary soft boiled eggs. And they’re not the same as poached eggs either. With poached eggs, the white is fully cooked. Not so with onsen eggs where the white is softer yet firm.
There’s science behind the cooking. Egg yolk and egg white solidify at different temperatures. The yolk at 70C and the white at 80C. If a whole egg in its shell is submerged in water with the temperature between 65C and 68C, you get a firm yolk that’s still runny at the center and a white that’s silky soft like custard.
There are plenty of formulas that you’ll find on the web. Some require leaving the eggs in the hot water for as long as 30 minutes. I cook my onsen eggs for 12 minutes.
I start by boiling a liter of water in a pot. Once it’s boiling profusely, I turn off the heat and pour in 200 milliliters of room temperature water.
I slide in the eggs, cover the pot and leave the eggs in the hot water for 12 minutes.
(Should the eggs be kept in the refrigerator prior to cooking? Some cooks recommend that. But my eggs were at room temperature and I’m happy with the result. I will try making onsen eggs again soon with eggs chilled in the fridge overnight, and let you know how that comes out.)
Now, this is essential. Once the eggs are out of the hot bath, they need a cold bath. I drop them in iced water to immediately stop them from cooking farther and leave them there until cold.
I crack the egg into a bowl, drizzle in a mixture of dashi, soy sauce and mirin. Toasted sesame seeds and scallions are sprinkled on top and the egg is ready to be enjoyed. By itself, with rice or with bread.
Hot spring egg (onsen tamago)
Ingredients
- 6 large eggs at room temperature
Sauce
- 6 tablespoons dashi
- 6 teaspoons soy sauce
- 6 teaspoons mirin
Garnish
- toasted sesame seeds
- sliced scallions
Instructions
- Boil a liter of water in a pot. Turn off the heat. Pour in 200 milliliters of room temperature water.
- Slide in the eggs and cover the pot. Leave for 12 minutes.
- Scoop out the eggs and dump into a bowl of iced water.
- While the eggs cool, simmer the dashi, soy sauce and mirin for about two minutes.
- To serve, crack an egg into a bowl, drizzle in some sauce, top with scallions and sesame seeds and serve.
