Use our home chef Naoko’s popular recipe for delicious braised beef udon noodle soup topped with rich and creamy ontama style soft boiled egg to whip up a Japanese restaurant style meal right in the comfort of your own home.

Contributed by Naoko’s Kitchen

This month our partner, home chef Naoko, shares her udon noodle soup recipe made with juicy beef and creamy egg (Ontama). One of the staples of Japanese food culture during the colder months of the year, this udon noodle soup is meant to warm your body up and is a little more complex than many of the other recipes on our site. And that’s because we are showing how to do it just like you would find it in a Japanese restaurant or traditional home dinner! We have previously posted Naoko’s recipe for udon soup with wasabi and ginger lamb balls. This one has a milder flavor but is more hearty and just as warming. Enjoy!

What Is Ontama?

Ontama is a short form for “Onsen Tamago”, which translates to “hot spring egg”. That is because it was originally cooked right in the steaming waters of natural hot springs (Onsen). The result is perfectly soft and silky egg yolk and soft egg white that melts in your mouth. Now ontama is a staple of Japanese culture and traditions and is cooked in homes all across the country.

So What’s the Difference From a Boiled Egg?

Ontama isn’t just a basic boiled egg. Eggs usually harden from the outside, so regular soft boiled eggs have hard egg whites with soft yolks. Instead, this technique uses eggs’ unique nature to slow cook them so that the egg yolk hardens (but still stays creamy and soft) while keeping the egg white silky soft. This gives ontama a distinctively creamy and rich texture that will change the way you think about boiled eggs forever!

How to Cook Ontama

Think of it like this: When you’re in a hot spring, your body’s core warms up, right?. Ontama is the same thing. The egg’s core (yolk) warms up before the outside, hence the name. Regular hot springs are about 150F degrees, so if you soak an egg in hot springs for about 30 minutes, you get ontama (150F is too low for egg whites to harden, but a perfect temperature, if slow-cooked, for egg yolks to cook).

This is because of eggs’ unique nature: egg yolks harden at a lower temperature than egg whites. Basically, egg whites start to harden at about 136F and completely harden at about 176F. Egg yolks harden at about 158F. Therefore, slow-cooking at a lower temperature uses this difference between the hardening temperatures of yolks and whites to get silky soft egg whites while making sure the yolk cooks. Got it?

Cooking Tips

  • If you don’t have kelp and bonito flakes, you can easily substitute dashi broth with dashi powder. You can get dashi powder online at an Asian grocery or at some grocery stores’ international section.
  • When making ontama, a key step is to add a cup of cold water into the boiling water. It’ll lower the temperature for the egg to slow cook from the core.
  • Ontama goes well with many dishes. It might take some practice, but it’s a good skill to master to add something extra to the table. There is nothing quite like its delicious silky texture and consistency!

The ultimate guide to many varieties of dashi broth, here.

Meet Naoko’s Kitchen

Naokos kitchen logo

Naoko’s Kitchen is brought to you by Japanese cook and Culinary Artist Naoko Kashiwagi who is living in the UK. Naoko has been sharing her authentic taste, knowledge, and skills of Japanese food by hosting pop-ups and Japanese cooking classes in Cornwall, UK. More than a thousand foodies from all over the world have participated in her informative and hands-on classes. They all enjoyed the entertainment of her exquisite dishes!

Naoko’s Kitchen is the first authentic Japanese pop-ups in Cornwall. This style allows her to collaborate with a lot of local businesses aiming at supporting each other as well. Her mission is simple. To entertain the customers with authentic Japanese flavors by adding subtle European twists to create innovative dishes.

Its concept promises to create family favorites using the freshest local seafood and seasonal ingredients with Naoko’s imagination and creativity. She creates a dish mixing authenticity with innovation for your taste buds and eyes.

Udon Noodle with Braised Beef and Soft Boiled Creamy Egg

Recipe by Naoko's Kitchen

Cuisine Japanese


  • 2 portion Udon Noodle
  • 1 Spring Onion, chopped
  • 2 Egg
  • Sprinkle of Shichimi Powder (optional)


  • ¼ lb Beef Shoulder
  • 1 Onion
  • 1 pinch Sea Salt
  • 1 Tbsp Sun Flower Oil
  • ½ cup Water
  • 1 tbsp Dashi Powder
  • 3 Tbsp Soy Sauce
  • 3 tsp Sake
  • ½ tsp Sugar

Dashi Broth

Noodle Soup

  • 1 cup Water
  • 1 ½ cup Dashi Broth
  • 1/3 cup Soy Sauce
  • ¼ cup Sake
  • 1 tsp Sugar
  • 2 pinch Sea Salt


Cook the beef

  1. Thinly slice the beef.
  2. Slice the onion.
  3. Pour the oil in a frying pan and stir the beef and onion over high heat.
  4. Add sugar, pinch of sea salt, soy sauce, water, dashi powder, and sake. Simmer until the onion turns tender and translucent.
  5. Remove from heat and set it aside.

Make dashi broth.

  1. Soak the kelp in water overnight in a fridge or for 2 hours in a room temperature.
  2. Transfer the kelp and water into small pot. Bring the water to boil and when it’s about to boil (167F-176F), turn off the heat and remove the kelp from the water.
  3. Add dried bonito flakes and simmer for 1 minute until all flakes sink to the bottom of the pot.
  4. Line a large strainer with a paper towel place it in a larger bowl. Strain the broth to remove bonito flakes.
  5. Gently squeeze the kitchen paper to release any remaining broth into the bowl.

Make dashi broth (alternative method).

  1. If you are in a hurry, you can make the broth with dashi powder.
  2. Combine 1 ½ cup of water and 2 tablespoon of dashi powder in a small pot.
  3. Bring to boil.

Make noodle soup.

  1. Pour 1 ½ cup of dashi broth into a small pot. If you’re using the alternative method, continue to step 2.
  2. Add water, sugar, sea salt, soy sauce, and sake to the broth and bring it to boil.

Meanwhile make the soft boiled creamy egg.

  1. Boil 1 quart water in a deep sauce pan (ideal to use thick iron sauce pan). Once the water boil, remove the pan from the heat and pour 1 cup of cold tap water. Immediately put the eggs in the water using a ladle.
  2. Put the lid on and let it sit for 12 minutes in a room temperature.
  3. Remove the eggs from the water and rest them 4 more minutes in a room temperature.
  4. Place them in the fridge until ready to use.

Make the udon.

  1. Boil the udon noodles according to the instruction on the package. Drain.
  2. Put the cooked udon noodles in a serving bowl and pour the hot noodle soup. Add the beef on top, crack the egg and sprinkle spring onions.
  3. Sprinkle Japanese seven chilli powder (shichimi) if you like.