In the past I’ve shared some popular Japanese egg recipes here on my blog such as Omurice, Tamagoyaki, and Ramen Egg (Ajitsuke Tamago). Today I’ll add another popular dish to the egg recipe collection, and it’s Onsen Tamago (温泉卵).
What’s Onsen Tamago?
Onsen means hot springs, and tamago means eggs in Japanese. Why is the name “hot springs eggs”? Originally, eggs that were prepared this way were slow cooked in Japan’s warm hot springs water.
What’s so special about these eggs? These eggs are perfectly poached inside its shell. While the whites are soft and silky, the yolk comes out firm, but retains the color and creamy texture of an uncooked yolk. It’s basically the complete opposite of soft boiled eggs that are firm whites and soft egg yolk.
The Chemistry Behind Onsen Tamago
This special texture is achieved because egg yolk and egg white solidifies at different temperature. Egg yolks solidify at 158 degrees °F (70 °C) and egg whites solidifies at 176 degrees °F (80 °C). Therefore, if we maintain the cooking water to be at 149-154 degrees °F (65-68 °C), we’ll get a perfect spherical poached egg, creamy and silky on the outside and firm on the inside.
This Recipe Works for EVERYONE.
There are many ways to make the perfect onsen tamago, but this technique does not require a microwave, a thermometer, or any special cooking gadget.
Here are the highlights of this technique:
- Requires just a stove and pot (which I hope everyone has in their kitchen).
- Does NOT require a thermometer.
- Use refrigerated eggs. Some recipes require eggs to be “room temperature”, but the “room” temperature could be different depends on where you live.
- Not required to soak eggs in iced water after cooking, in case you don’t have ice cubes handy.
If you follow my recipe precisely, you should be able to achieve perfect onsen tamago as the final result. The only requirement is to use 4 large eggs. If you use different size eggs or reduce/increase the number of eggs, it will not work as the water temperature will change.
How Do you Enjoy Onsen Tamago?
You can enjoy onsen tamgo with a dashi-based soy sauce (だし醤油) which is usually served as a part of Japanese breakfast. Also, you can place it on top of the steamed rice, splash some soy sauce over, mix and enjoy; serve with gyudon, curry rice, soba noodle soup, and cold udon; or even mix with carbonara (my favorite!).
Now let’s get started! The best part about this recipe is you do not need to visit hot springs in Japan to enjoy these special eggs. Make the perfect onsen tamago right at home!
Disclaimer: Many people in the world including the Japanese consume uncooked eggs in their cuisine. However, according to the FDA, eggs should be cooked to 165 degrees °F (74 °C) in order to be considered safe. The perfect temperature for cooking onsen tamago is 149-154 degrees °F (65-68 °C), which is below the guideline. There is a risk of salmonella with consuming undercooked eggs.
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- 1 liter (about 4 cups) water
- 200 ml (little bit less than 1 cup) tap water (needs to be colder than room temp)
- 4 large eggs, refrigerated
- ¼ cup dashi (vegetarian kombu dashi)
- ½ Tbsp. mirin
- 1 ½ Tbsp. soy sauce
- 3 g katsuobushi (dried bonito flakes) (skip for vegetarian)
- 1 scallion/green onion for garnish
- 2.5 QT saucepan with lid (make sure water will cover eggs)
- A ladle or mesh strainer
- A large mesh strainer
- Add 1 liter water in a heavy bottom saucepan, cover and bring it to a boil.
- Once boiling, remove the pot from the heat. Take the eggs out from the refrigerator. Add 200 ml cold tap water and gently submerge the cold eggs in the hot water. Immediately cover and set timer for 17 minutes (or longer).
- If you like to enjoy onsen tamgo with the sauce, combine the dashi, mirin, and soy sauce in a small saucepan and bring it to a boil. Add katsuobushi and turn off the heat, let katsuobushi sink at the bottom of the pan. After 30 seconds or so, strain through the strainer and set the sauce aside. You can keep the sauce in refrigerator for 4-5 days.
- Cut scallion into thinly slices and set aside.
- Once 17 minutes have passed, take the eggs out gently and set aside for 5 minutes.
- You can enjoy onsen tamago either cold or warm. Crack the egg and pour the sauce over, garnish with chopped scallion. You can keep the onsen tamago for 1-2 days in the refrigerator.