Never boil the dashi once the bonito goes in. Kombu steeps in water below a simmer, and bonito flakes are added off the boil and strained fast; boil either and the broth turns bitter and fishy instead of clean and savory.
By Vince Gonzalez · Published July 2026 · Sourcing verified 5 Jul 2026
Prep10 min
Cook20 min
Makesserves 4
CuisineJapanese
Cost$
Dairy-free
Contains gluten · fish · soy
Make it gluten-free: swap in a gluten-free pasta or noodle (check the other labels too).
The Ingredients — and where to get them
Cook for4servings
Udon noodles
Thick wheat udon, frozen or fresh beats dried for that chewy bounce.
4 portions
Local / market
Kombu
Dried kelp; steep it slow in cool water, never boil it.
1 large piece
Local / market
Bonito flakes
Katsuobushi; add off the heat and strain within minutes.
2 cups loosely packed
Local / market
Soy sauce
Light soy (usukuchi) keeps the broth pale; regular works too.
Can you make Udon Noodle Soup in an air fryer? — Yes, with an insert
Not on its own — an air fryer can’t hold a pool of liquid. You can simmer it in an oven-safe dish or a silicone insert made to fit the basket, but the broth won’t reduce or brown the way it does on the stove, and that insert comes out scorching, so use oven mitts. For real depth, a pot on the stove wins.
Can you freeze Udon Noodle Soup? — Yes
Yes — it freezes well. Cool it fully, portion into airtight containers, and it keeps a few months; thaw in the fridge and reheat gently.
Can you make Udon Noodle Soup ahead of time? — Yes
Yes — it holds well and often tastes better the next day. Make it ahead and reheat gently before serving.
Is Udon Noodle Soup gluten-free? — Not as written
Not as written — it contains gluten. Make it gluten-free: swap in a gluten-free pasta or noodle (check the other labels too).
Is Udon Noodle Soup vegan? — No
No — it contains seafood, so it isn’t vegetarian or vegan.
Community Notes
Cooked it? Changed something that worked? Leave a note for the next person — first-name basis, no account.