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Vegan Soba Noodle Soup (Sansai Soba)

This soba noodle soup features fresh spring veggies, crispy tofu, bamboo shoots, and mushrooms in a smoky, savory broth with toothy buckwheat noodles. It’s both refreshing and hearty - a slurpable and soothing one-bowl meal.
Prep Time10 mins
Cook Time45 mins
Course: Dinner
Servings: 2
Author: Thomas


  • 2 servings soba noodles dried or fresh
  • 1 cup sansai optional (see note)
  • 2 sheets aburaage cut into slices (or substitute 1 cup cubed tofu)

Veggies and mushrooms to blanch

  • 1 cup chopped asparagus
  • 1 cup chopped broccolini
  • 1 cup chopped spinach
  • 1 cup shimeiji mushrooms or enoki or other mushrooms


  • 1/2 cup sake
  • 6 cups water
  • 1/4 teaspoon liquid smoke
  • 3 dried shiitake mushrooms sliced
  • 1 piece kombu seaweed 2x2 inches or 5x5 centimeters
  • 1/2 sheet sushi nori seaweed 8x4 inches or 20x10 centimeters
  • 4 large coin-sized slices of ginger
  • 1 teaspoon maple syrup
  • 4 Tablespoons soy sauce

Optional garnishes

  • Radish sprouts
  • Green onions sliced thinly
  • Shichimi Togarashi


  • If using aburaage, preheat the oven to 400 degrees F or 205 degrees C.
  • Prepare two pots on the stove - one medium-sized one (2.5 quarts or 2.3 liters) for the broth and a large one (5 quarts or 4.7 liters) to cook the noodles and blanch the vegetables and mushrooms.
  • Fill the large pot 2/3 of the way with water and heat it over high heat.

Simmer the Broth

  • Combine all the Broth ingredients in the medium-sized pot, except for the maple syrup and soy sauce (you’ll add those two at the end). Bring the mixture to a simmer over medium heat, then reduce to medium-low heat. Simmer for at least 30 minutes to infuse the flavors.

Bake the Aburaage

  • Once the oven is preheated, place the sliced aburaage onto a baking sheet and bake for 10 minutes, or until crispy.

Boil the noodles and vegetables

  • Meanwhile, when the large pot of water reaches a boil, boil the noodles according to the instructions. You can even undercook them slightly, since they will continue to absorb liquid and soften one they’re combined with the broth. Remove the noodles, strain them, and rinse them with cool tap water to stop the cooking.
  • If you’re using cubed tofu (not aburaage), blanch the tofu cubes for 1 minute.
  • Cook the vegetables and mushrooms individually in the large pot. The asparagus, broccolini, and mushrooms need 30-45 seconds and the spinach needs about 10 seconds. Pay attention to the color of the vegetables - you want them to stay bright green for the best flavor and texture. Remove each vegetable from the pot, strain it, and rinse it with cool tap water.
  • You can blanch the sansai for 10 seconds to heat it up, but it’s already cooked, so this step is optional.

Strain and Season the Broth

  • By now, the broth should be well-infused. Strain out as much of the solids as possible. The nori will have disintegrated, so use a fine mesh strainer or cheesecloth to remove as much as you can.
  • Stir the soy sauce and maple syrup into the broth.

Combine, garnish, and serve

  • Divide the noodles, vegetables, and mushrooms evenly into two large bowls. Spoon broth over top of them until the bowl is nearly full. Add the crispy aburaage. Garnish with radish sprouts, green onions, or shichimi togarashi, as desired. Serve immediately.


If you don’t have sansai, you can increase the amounts of the other vegetables and mushrooms by 1/4 cup each.