In a medium saucepan, bring the Vegetarian Dashi to a low simmer.
Stir in the soy sauce, mirin, and sake. Allow the broth to simmer gently for 5 minutes to meld the flavors.
While the broth simmers, bring 4 quarts / 3. 75 liters of unsalted water to a boil in a large pot.
Add the soba noodles and cook for about 7 minutes, or until cooked through but still firm (al dente).
Drain the noodles in a colander and rinse them thoroughly with warm water to remove excess starch.
Divide the rinsed noodles evenly among 4 serving bowls. Ladle 1 cup / 250 ml of the hot broth over the noodles in each bowl.
Top each bowl equally with the Vegetable Tempura pieces, inari strips, nori strips, and sliced green onions.
Serve immediately.
Add the tempura to the soup immediately before serving. This is the golden rule to ensure it stays crispy and doesn't become soggy.
Don't skip rinsing the soba noodles. Rinsing removes the surface starch, which prevents the noodles from clumping and keeps the broth clear.
Keep the broth at a gentle simmer after adding the seasonings. A hard boil can evaporate the delicate aromas of the mirin and sake.
