Zaru-Soba

To prepare the dashi, gently wipe the kombu with a damp cloth. Place the kombu and 500g water in a pot and heat 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. Strain the dashi through a fine-mesh sieve, discarding the katsuobushi.

In a separate saucepan, combine the strained dashi, soy sauce, mirin, and sake. Bring the mixture to a gentle simmer over medium heat, then immediately remove from heat. Let the tsuyu cool completely, then chill in the refrigerator.