Udon noodle soup
Comforting Japanese noodle soup with homemade dashi, tender udon, shiitake and tofu — clean, savoury and ready in under an hour.
This is a straightforward bowl of udon noodle soup that sings because of a simple homemade dashi. It’s deep, clean and far superior to anything from a packet — and not as fiddly as you might imagine.
Make it on a blustery evening or when you need something soothing but not heavy. The recipe is flexible: switch toppings to suit the fridge, but keep the dashi — it’s the soul of the dish.
Ingredients
- 1 1/2 l water
- 10 g kombu
- 20 g katsuobushi
- 45 ml light soy sauce
- 30 ml mirin
- 30 ml sake
- 5 g granulated sugar
- 400 g fresh udon noodles — use fresh refrigerated udon; if using dried increase cooking time per packet instructions
- 150 g shiitake mushrooms — stalks removed, sliced
- 200 g soft tofu — cut into 2 cm cubes
- 120 g baby spinach
- 10 g dried wakame — will rehydrate
- 3 spring onions — trimmed and finely sliced
- 5 ml sesame oil — toasted sesame oil for frying
- 10 g toasted sesame seeds — for sprinkling
Equipment
- fine sieve
- colander
- ladle
Instructions
Put the water and kombu in a large saucepan and leave to soak at room temperature for 30 minutes.
Place the saucepan on a medium heat and warm the water until tiny bubbles appear around the edge (just below simmer). As soon as you see the bubbles, remove the kombu with tongs and discard.
Add the katsuobushi, bring back to a very gentle simmer for 30 seconds, then remove from the heat and leave the flakes to steep for 5 minutes. Strain through a fine sieve and return the clear dashi to the pan.
Stir the light soy sauce, mirin, sake and granulated sugar into the strained dashi and warm gently until just under a simmer, about 3 minutes. Taste and adjust seasoning — add a little more soy if you want it saltier.
Put the dried wakame in a small bowl and cover with warm water. Leave to rehydrate for 5 minutes, then drain, squeeze out excess water and roughly chop if large.
Bring a separate large pan of water to a rolling boil and cook the fresh udon noodles for 2–3 minutes until just tender. Drain briefly in a colander and divide between four bowls.
Meanwhile, heat the sesame oil in a frying pan over medium heat and sauté the shiitake mushrooms for 3–4 minutes until lightly browned and tender.
Rewarm the seasoned dashi if needed, then ladle hot broth over the noodles. Top each bowl with cubes of soft tofu, sautéed shiitake, a handful of baby spinach (it will wilt in the heat), the rehydrated wakame and sliced spring onions. Finish with a sprinkle of toasted sesame seeds.
Serve immediately while piping hot. If you like, pass extra soy sauce and chilli oil at the table.
Tips
- Don’t boil kombu — remove it just before the water reaches a simmer to avoid bitterness.
- If you’re short on time use a good-quality ready-made dashi stock, but reduce the added soy slightly and taste as you go.
- For clearer broth strain through a fine sieve or cheesecloth and avoid stirring katsuobushi while steeping.
- Cook udon at the last minute and assemble immediately so noodles don’t go soggy; if making ahead keep noodles and broth separate.
- Leftover soup keeps well for 24 hours in the fridge; reheat gently and add a splash of water if the broth has reduced.
Substitutions
katsuobushi → 10 g extra kombu plus 8 g dried shiitake (to make a vegetarian dashi)
Stays closefresh udon noodles → dried udon per packet instructions (increase cooking time by a few minutes)
Stays closesoft tofu → 200 g firm tofu, pan-fried until golden
Noticeably differentsesame oil → neutral vegetable oil (less sesame aroma)
Noticeably different
Nutrition
Per serving · estimated
- 214
- Calories
- 10 g
- Protein
- 30 g
- Carbs
- 6 g
- Fat
- 2 g
- Fibre
- 3 g
- Sugar
- 800 mg
- Sodium
FAQ
Can I make the dashi ahead?
Yes — make dashi and keep it in the fridge for up to 48 hours or freeze in portions for up to 2 months.
How do I make this vegetarian?
Replace the katsuobushi with extra kombu plus dried shiitake to create a rich vegetarian dashi.
What type of udon should I use?
Fresh refrigerated udon gives the best texture. If unavailable, use dried udon and follow packet timings.
Can I add protein like chicken or prawns?
Yes — briefly poach sliced chicken or add cooked prawns to hot broth before serving; adjust seasoning as needed.
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