8 dried shiitake mushrooms
3/4 cup of sake
1/2 cup of tamari
1 tablespoon of mirin
2 pinches of salt
1/4 teaspoon of fresh lemon juice
2 sheets of nori, thinly shredded
4 scallions, thinly sliced on the diagonal
2 tablespoons of sesame seeds, toasted and ground
2 teaspoons of wasbi powder, mixed with just enough water to form a soft paste
1 2-inch piece of daikon, peeled and grated
1 2-inch piece of ginger, peeled and grated
To Prepare the Dashi:
In a small sauce pan, bring 2 3/4 cups of water and the dried mushrooms to the boil. Reduce the heat to low, cover, and simmer for 1 hour.
Transfer the mushrooms to a small bowl with a slotted spoon and reserve for another use.
Strain the broth through a fine sieve of a coffee filter placed in a strainer set over a medium saucepan to remove any dirt.
Add the sake, the tamari, the mirin, and the salt to the mushroom broth and bring to the boil. Reduce the heat to low and simmer until the alcohol aroma disappears, about 15 minutes.
Remove the dashi from the heat and add the lemon juice. Serve.
While cooking the alcohol from the dashi, bring a large pot of water to the boil. Add the soba and cook until the desired doneness is achieved, anywhere form 5 to 8 minutes.
Drain the soba, rinse well under cold water, using your hands to gently swish the noodles, and drain again. Repeat.
Divide the soba among 4 to 6 bowls, swirling each serving into a mound. Sprinkle each mound with some of the shredded nori.
Place 1/2 to 3/4 cup of hot dashi in separate bowls alongside each serving of soba.
Serve the remaining condiments on a small platter or in little bowls at the center of the table so the diners may help themselves.