How to make onsen tamago: perfect Japanese hot spring eggs

Onsen Tamago

Onsen tamago is a traditional Japanese dish that consists of eggs cooked in hot spring water.

The result is a soft and silky egg white with a custard-like yolk that melts in your mouth.

Onsen tamago (in Japanese 温泉卵 or 温泉玉子, which literally means ‘hot spring egg’) is usually served with a dashi-based soy sauce, but you can also enjoy it on top of rice, noodles or even a Japanese style carbonara pasta.

In this blog post, I will show you how to make onsen tamago at home using a simple technique that does not require any special equipment!

What is onsen tamago?

Onsen tamago literally means “hot spring egg” in Japanese.

It refers to eggs that are slowly cooked in the shell in natural hot spring water to create a unique texture.

The egg white is soft and runny, while the yolk is firm but creamy.

The secret behind this texture is the difference in the temperature at which egg white and egg yolk solidify.

Egg whites start to harden at 58°C (136°F), but they do not fully set until they reach 80°C (176°F).

On the other hand, egg yolks harden at around 65-70°C (149-158°F). Therefore, if you keep the water temperature between 65-70°C (149-158°F), you can achieve onsen tamago.

Why is it called onsen tamago?

Onsen tamago got its name from the fact that it was originally cooked in hot springs in Japan.

Japan is a volcanic island with many natural hot springs, or onsen, that vary in temperature from 25°C (77°F) to 98°C (208°F). Some of these hot springs have the perfect temperature for making onsen tamago, around 70°C (158°F).

Egg yolks solidify at 158°F (70°C), and egg whites solidify at 176°F (80°C).

People would bring fresh eggs and put them in the hot spring water to make boiled eggs.

This method was not only convenient but also added a subtle mineral flavor to the eggs.

Tips for making the perfect onsen tamago

Here are some tips to help you make perfect onsen tamago every time:

  • Use refrigerated eggs that are large in size. Smaller or room-temperature eggs may cook faster and result in different textures.
  • Use a thick pot that can retain heat well. This will help keep the water temperature consistent while cooking the eggs.
  • Use a thermometer to monitor the water temperature. The ideal range is 149-154°F (65-68°C). Maintain this temperature consistently throughout the cooking process.
  • Do not overcook or undercook the eggs. Overcooked eggs will have rubbery whites and dry yolks, while undercooked eggs will have runny yolks and watery whites.

How to make onsen tamago at home

You don’t need to visit a hot spring in Japan to enjoy onsen tamago.

You can make it at home with just a pot, a stove and some eggs.

Here are the steps to follow:

  1. Bring a small pot of water to a boil over high heat. Then turn off the heat.
  2. Carefully lower 3 large eggs (straight from the fridge) into the hot water using a slotted spoon or a ladle. Make sure the eggs are completely submerged in the water.
  3. Leave the eggs there for 20 minutes, don’t cover the pot.
  4. Once that is done, transfer the hot eggs to a bowl of cold water to stop the cooking process or since them under cold running tap water for a couple of seconds.
  5. Peel, pour the eggs in separate little bowls and enjoy!

How to serve onsen tamago

Onsen tamago is delicious on its own, served on their own as a simple and delicious snack or appetizer.

Simply crack the egg open and eat it with a spoon, or scoop the egg out of the shell and enjoy.

You can also serve it with different sauces and toppings.

Here are some ideas for you to try out!

  • Dashi and soy sauce: This is the most common way to enjoy onsen tamago, and the way I like my hot spring eggs best. Simply mix some dashi stock, soy sauce, mirin and sugar in a small bowl and drizzle it over the eggs.
  • Rice: Place an onsen tamago on top of a bowl of steamed rice and add some soy sauce or furikake seasoning for a simple and satisfying meal. The runny yolk will mix with the rice, creating a delicious and creamy sauce.
  • Noodles: Add an onsen tamago to your favorite noodle soup, such as soba, udon or ramen, for extra protein and richness. The runny yolk will mix with the noodles and broth, creating a rich and flavorful dish.
  • Carbonara: Mix an onsen tamago with cooked spaghetti, bacon, cheese and black pepper for a creamy and decadent pasta dish.
  • Salad: onsen eggs can be a great addition to salads, adding a rich and creamy texture to the dish. Simply slice the egg in half and place it on top of the salad.
  • With sushi: onsen eggs can be used as a topping for sushi, adding a unique and delicious flavor to the dish.

Onsen tamago is one of my favorite Japanese comfort foods. It is easy to make, versatile to serve, and always satisfying.

I hope you give it a try and let me know what you think!

Is onsen tamago really safe to eat?

Yes, onsen tamago is generally safe to eat, provided that it is prepared and cooked properly.

The cooking process, which involves immersing the eggs in hot water, helps to kill off any harmful bacteria that may be present on the surface of the egg.

However, it is important to note that onsen tamago is a raw or partially cooked food, and as such, there is always a risk of foodborne illness. This risk is particularly high for people with weakened immune systems, such as the elderly, young children, pregnant women, and individuals with chronic illnesses.

To reduce the risk of foodborne illness when preparing and consuming onsen tamago, it is important to use fresh, high-quality eggs and to follow proper food safety practices. This includes washing your hands thoroughly before handling the eggs, using clean utensils and equipment, and cooking the eggs to the appropriate temperature and time.

If you are concerned about the safety of onsen tamago or any other raw or partially cooked food, it is always best to consult with a healthcare professional or food safety expert for guidance.

They can help you understand the risks and provide you with tips and recommendations for safe preparation and consumption.

How long can I store these hot spring eggs in the fridge?

You can keep them uncracked for 1 to 2 days in the refrigerator.

To reheat the egg, remove it from the refrigerator and bring it to room temperature. To warm it up further, place it in a bowl of 160°F (70°C) water for 10 minutes.

Is onsen tomato the same as a poached egg?

While onsen eggs and poached eggs are similar in that they are both cooked in water, there are some key differences between the two.

Onsen eggs are traditionally cooked in hot springs or hot water baths, whereas poached eggs are typically cooked in a pot of simmering water on a stove. The temperature of the water used to cook onsen eggs is typically lower and more consistent than the temperature used for poaching eggs. This results in a slightly different texture and flavor for the eggs.

Additionally, onsen eggs are usually cooked for a longer period of time than poached eggs. The whites of onsen eggs are set and cooked all the way through, while the yolks are still runny. Poached eggs, on the other hand, are usually cooked for a shorter period of time, so that the whites are set but the yolks remain runny.

In terms of taste and texture, onsen eggs are often described as having a smoother, creamier texture and a more delicate flavor than poached eggs. This is due in part to the lower cooking temperature and longer cooking time, which results in a gentler cooking process that doesn’t toughen the egg whites as much.

Overall, while both onsen eggs and poached eggs are delicious and nutritious ways to prepare eggs, they are slightly different in terms of their cooking method, temperature, and texture.

Overall, onsen eggs are a versatile ingredient that can be used in a variety of ways.

Whether you are serving them on their own or using them as a topping for other dishes, they are sure to add a rich and delicious flavor to your meal.

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