Nishin Soba

Rehydrate the dried herring by soaking it in plenty of water overnight, changing the water several times. Once softened, carefully remove any remaining bones and scales.

In a medium pot, combine the rehydrated dried herring, sake, mirin, koikuchi soy sauce, sugar, and water for simmering herring. Bring to a gentle simmer over medium heat, then reduce heat to low, cover, and simmer for 60-90 minutes until the dried herring is very tender and has absorbed the sweet-savory flavor. Set aside.

To prepare the dashi, place the kombu in a pot with water for dashi and let it soak for at least 30 minutes. Heat the pot over medium-low heat. Just before the water boils, remove the kombu. Bring the water to a boil, then turn off the heat and add the katsuobushi. Let it steep for 5 minutes, then strain the dashi through a fine-mesh sieve, discarding the katsuobushi.