Kake Soba (Hot Soba Noodles)

Prepare the dashi stock: Gently wipe the Kombu with a damp cloth to remove any impurities. Do not wash or scrub. Place the Water and Kombu in a pot and slowly heat over medium-low heat. Just before the Water comes to a boil, remove the Kombu. Add the Katsuobushi to the simmering Water and bring to a gentle boil for 30 seconds, then immediately turn off the heat. Let the Katsuobushi settle for a minute, then strain the dashi through a fine-mesh sieve, discarding the solids.

Make the soba broth (tsuyu): Return the strained dashi to the pot. Add the Usukuchi soy sauce, Mirin, and Sake. Bring the mixture to a gentle simmer over medium-low heat, stirring occasionally. Do not boil vigorously. Taste and adjust seasoning if necessary.

Cook the Soba noodles: Bring a large pot of Water to a rolling boil. Add the Soba noodles and cook according to package instructions, typically 3-5 minutes, stirring occasionally to prevent sticking. The noodles should be al dente. Drain the Soba noodles thoroughly in a colander.