Lean into the unique textures and refreshing flavors of Cold Natto Udon. Topped with vegetables and a Japanese-style poached egg, this chilled noodle dish is a great way to enjoy Japanese fermented soybeans on a hot summer day! Ready in just 20 minutes.
This Cold Natto Udon is for anyone who appreciates the bold and sprightly characters Japanese food has to offer! Picture this: umami yet slimy natto, subtly sweet with earthy undertones of okra, spicy and tangy kimchi, crunchy and cooling cucumber, sour pickled plum, and a runny poached egg served over slippery, chilled udon noodles. It’s an explosion of colors, flavors, and textures—perhaps a noodle dish you never knew you loved.
Ready to discover and make this recipe at home? Let me show you how!
Table of Contents
All About Neba Neba Texture
If you have been following Just One Cookbook for a while, you have certainly heard me talking about neba neba (ネバネバ) when describing certain foods. For those who are unfamiliar, neba neba is a Japanese term for foods with a slimy texture. These foods are considered nutritious and good for strengthening the body and recovering from fatigue, especially for preventing summer fatigue.
As you can tell from the cold udon dish, I’ve incorporated quite a few slimy foods here, including natto, okra, and grated mountain yam (nagaimo). Each ingredient has its own unique personality and is high in fiber, antioxidants, and minerals.
I’d also want to highlight that natto is the key topping as we often enjoy natto with cold udon in the summertime. It makes a light yet nutritious meal, with plenty of room for improvisation.
Why You’ll Love This Recipe
- Bursting with exciting and uniquely Japanese tastes and textures.
- Absolutely fabulously delicious. Granted, it’s not for everyone, but if you have adventurous and expansive tastebuds, you’re going to love it!
- Jam-packed with antioxidants and nutrients, as it is composed with superfoods in a bowl.
Ingredients You’ll Need
To create the best version of Cold Natto Udon, I’ve carefully selected the toppings with considerations of health benefits and complementary flavors and textures. It is a slightly long list, but they don’t take long to prepare. If you prefer to keep things simple, feel free to leave out some toppings, except the natto.
For the toppings:
- Okra (Ladies’ fingers) —This special vegetable peaks during the summer, so it’s prime time to enjoy it.
- Japanese or Persian cucumber
- Onsen tamago (Japanese poached egg) — To save time, I poach the egg by using the 2-Minute Microwave Onsen Tamago method.
- Shiso leaves (perilla/ooba) — Add a herbaceous and refreshing aroma. Skip it if you can’t find the herb.
- Umeboshi (Japanese pickled plum) — The sour taste helps improve the flavor of natto.
- Natto (fermented soybean) — This is the star topping, so don’t skip it!
- Kimchi — The slightly pungent, sourish, spicy, and tangy kimchi contrasts beautifully with the rest of the ingredients
- Nagaimo/yamaimo (mountain yam) — Feel free to leave this out as it might be hard to find, but if you can access nagaimo, I highly recommend it. The gooey texture of grated yam lends an indescribable enjoyment to the overall taste of the dish!
- Toasted white sesame seeds
For the noodle:
- Udon noodles — I recommend using only the frozen ones for the best texture.
For the Sauce
- Mentsuyu (concentrated noodle soup base) – Store-bought or make your own following my recipe.
- Water
- Ice cubes
How to Make Cold Natto Udon
- Prepare the toppings. Blanch and cut the okra into thin slices, julienne the cucumber, chiffonade the shiso leaves, mince the umeboshi, and poach the egg in the microwave.
- Open the natto package, add the sauce, umeboshi, and shiso, and stir to mix well.
- Cook udon noodles. In the meantime, prepare the sauce.
- Chill the cooked udon and transfer to a plate.
- Top with prepared toppings.
- Grate the yam and pour onto the udon. Top with sesame seeds. Serve immediately.
- Pour the mentsuyu sauce onto the cold udon noodles at the table and enjoy!
Recipe Tips
- Cut the ingredients into small, even pieces so you can enjoy the symmetrical texture when you mix them with the noodles.
- The sauce should be slightly saltier because the toppings will dilute the flavor.
- Mix natto really well with chopsticks to enhance the umami and overall enjoyment of the dish.
How to Store
The leftovers should be kept in an airtight container and stored in the refrigerator for up to 3 days or in the freezer for a month.
Cold Udon Dishes to Enjoy in the Summer
Since this Cold Natto Udon makes a complete meal on its own, we love to pair it with some cold Japanese beer or cold teas like Mugicha (Barley Tea), Cold Brew Hojicha, and Cold Brew Green Tea. And don’t forget to check out my two other cold udon recipes:
Wish to learn more about Japanese cooking? Sign up for our free newsletter to receive cooking tips & recipe updates! And stay in touch with me on Facebook, Pinterest, YouTube, and Instagram.
Cold Natto Udon
Ingredients
For the Toppings
- 2 okra
- 1 Japanese or Persian cucumber
- 5 shiso leaves (perilla/ooba) (or more, to taste)
- 1 large egg (50 g each w/o shell)
- 1 umeboshi (Japanese pickled plums)
- 1 package natto (fermented soybean) (with sauce packet)
- 2 Tbsp kimchi
- 1 inch nagaimo/yamaimo (mountain yam)
- 1 tsp toasted white sesame seeds
For the Noodles
- 1 serving udon noodles (frozen; ½ lb, 250 g per serving)
For the Sauce
- 1 Tbsp mentsuyu (concentrated noodle soup base) (following the 1:3 dilution ratio for this mentsuyu brand; you can make homemade mentsuyu)
- 3 Tbsp water
- ice cubes
Instructions
- Gather all the ingredients.
To Prepare the Ingredients
- With a knife, cut off the stems of 2 okra but don‘t remove the entire top. Then, peel off the tough calyx around the top.
- Blanch the okra in a pot of boiling water for 2–3 minutes (or small okra for 1–2 minutes and large okra for 3–4 minutes). As soon as they are tender, drain in a sieve. Do not overcook. Slice crosswise into small pieces.
- Peel the skin of 1 Japanese or Persian cucumber in a striped pattern. Slice diagonally into thin oval slabs, then stack and julienne into matchsticks.
- Stack and tightly roll up 5 shiso leaves (perilla/ooba), then chiffonade crosswise into thin strips.
- Make a Japanese-style poached egg (onsen tamago) in the microwave. (For detailed instructions and step-by-step photos, see my 2-Minute Microwave Onsen Tamago recipe.) Crack 1 large egg (50 g each w/o shell) into a small, microwave-safe bowl. Pour in some water around the edges to push the egg to the center, then add just enough water on top to submerge the yolk. Puncture the yolk with a toothpick. Place in the microwave at the outer edge of the tray and heat at half power for 90 seconds or until the egg white just solidifies and turns white. Remove it from the water and transfer to a bowl.
- Discard the pit of 1 umeboshi (Japanese pickled plums), then chop the flesh.
- Open 1 package natto (fermented soybean) and add the sauce packet, umeboshi and shiso. Using chopsticks, mix it together really well. Tip: In Japan, they say to stir the natto 100 times. This incorporates air for a fluffy texture and releases the glutamate in the culture for improved umami.
To Assemble the Cold Natto Udon
- Bring water to a boil in a medium pot. Add 1 serving udon noodles and boil the frozen udon for 1 minute to heat through. Drain, then run the noodles under plenty of cold tap water to cool. If you‘d like, you can place the udon in cold water and add ice cubes to chill while you prepare the other ingredients.
- Make the sauce by combining 1 Tbsp mentsuyu (concentrated noodle soup base), 3 Tbsp water, and several ice cubes in a small jug with a spout.
- Transfer the cold udon to a plate. Add the okra, cucumber, onsen tamago, natto, and 2 Tbsp kimchi in neat piles on top of the noodles.
- Right before serving, peel and grate 1 inch nagaimo/yamaimo (mountain yam). I use a ceramic grater that I love. Note: The nagaimo may irritate your skin and cause itchiness. Work quickly and rinse your hands immediately after touching it or wear kitchen gloves. Nagaimo is very slimy and slippery, so make sure you have a good grip on it.
- Immediately pour the grated nagaimo onto the udon. Top with 1 tsp toasted white sesame seeds. Serve immediately. Pour the mentsuyu sauce onto the Cold Natto Udon at the table and enjoy.
To Store
- You can keep the leftovers in an airtight container and store in the refrigerator for up to 3 days and in the freezer for a month.
I’m the only one in my family who likes natto. Dear Husband and Dear Daughter are going hiking next week, so I think I will try this then. First a trip to Najiya as I’m running out of miso and I’m down to one package of natto which will be gone by then.
Hi Julia! Thank you for reading Nami’s post and trying her recipe!
We hope you enjoy this dish as much as we do! Happy Cooking!