Ajitsuke Nori

To prepare dashi, place kombu in a pot with water and let it soak for 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. Add katsuobushi to the hot water and let it steep for 5 minutes. Strain the dashi through a fine-mesh sieve, discarding the katsuobushi.

In a small saucepan, combine koikuchi soy sauce, mirin, sake, granulated sugar, and 100g of the prepared dashi. Heat over low heat, stirring constantly until the granulated sugar completely dissolves and the mixture is well combined. Do not boil. Remove from heat and let the seasoning liquid cool completely.