Japanese Soba Noodles in Dashi Broth with Vegetables

Other Fast Without Oil Published April 11, 2026

Soba — buckwheat noodles in hot dashi broth — is one of the most elegant simple meals in Japanese cuisine and one of the most naturally fasting-friendly. The broth is made from kombu (dried kelp) and dried shiitake mushrooms, building an intensely savory, umami-rich liquid without a drop of oil or any animal product. The noodles are cooked separately and slipped into the hot broth at the last moment so they stay firm and distinct.

This is Japanese temple food in spirit — refined, clean, and deeply satisfying in a way that has nothing to do with richness. The broth should taste like the ocean and the forest at the same time.

FASTING LEVEL: Fast Without Oil (cooked food permitted, no oil, no wine)
SERVINGS: 4
TIME: 30 minutes (plus 30 minutes soaking for the dashi)

INGREDIENTS

For the dashi broth:
- 1 large piece kombu (dried kelp), about 15cm
- 6 dried shiitake mushrooms
- 6 cups cold water
- 3 tablespoons soy sauce
- 1 tablespoon mirin (contains trace alcohol that cooks off — omit if strict, substitute 1 teaspoon sugar)
- 1 teaspoon salt

For the noodles and toppings:
- 300g dried soba noodles (check label — some contain wheat; 100% buckwheat soba is best)
- 4 leaves napa cabbage, sliced into ribbons
- 2 green onions, sliced thin on a bias
- 1 medium carrot, julienned thin
- 100g firm tofu, cut into small cubes
- Nori (dried seaweed), cut into strips, for garnish
- Shichimi togarashi (Japanese seven-spice), for serving (optional)

METHOD

1. Make the dashi. Place the kombu and dried shiitake mushrooms in a pot with 6 cups cold water. Let it soak for at least 30 minutes (or up to several hours — longer is better). Then place the pot over medium heat and bring slowly to just below a boil. The moment you see small bubbles forming at the edges, remove the kombu (boiling it makes the broth bitter). Leave the mushrooms in.

2. Let the broth simmer gently for 10 minutes. Remove the mushrooms, slice them thin, and set aside — they go back into the soup later. Season the broth with soy sauce, mirin (or sugar), and salt. Taste — it should be savory, slightly sweet, and deeply umami.

3. Add the napa cabbage and carrot to the simmering broth. Cook for 3-4 minutes until just tender. Add the tofu cubes and sliced mushrooms. Keep warm over low heat.

4. Meanwhile, cook the soba noodles in a separate large pot of boiling unsalted water according to the package directions — usually 4-5 minutes. Drain and rinse briefly under cold water to remove excess starch. This keeps the noodles firm and prevents them from turning the broth cloudy.

5. Divide the soba noodles among four deep bowls. Ladle the hot broth and vegetables over the noodles. Top with sliced green onions and nori strips. Serve with shichimi togarashi on the side for those who want heat.

NOTES

- Kombu and dried shiitake mushrooms are available at any Asian grocery store and increasingly at regular supermarkets. They keep indefinitely in a dry pantry.
- The kombu must not boil. Pull it out when the water reaches 80-85C — just below a simmer. This extracts the glutamic acid (natural MSG) without the bitter compounds.
- 100% buckwheat soba is naturally gluten-free and has a more robust, nutty flavor. Most commercial soba contains wheat flour, which works fine but is a different texture.
- Mirin technically contains alcohol (about 14%), but it cooks off during simmering. If this is a concern, substitute sugar and a splash of rice vinegar. Some strict fasters avoid it entirely — follow your own practice.