2To prepare dashi, place 10g Kombu and 500g Water in a pot and let it soak for 30 minutes. Heat the pot over medium-low heat. Just before the water boils, remove the Kombu. Add the Katsuobushi to the hot water and simmer for 30 seconds. Turn off the heat and let the Katsuobushi settle for 5 minutes. Strain the dashi through a fine-mesh sieve, discarding the solids.
3To prepare the simmered kombu topping, rehydrate 30g Dried Kombu in water for 15 minutes until softened. Drain and thinly slice the rehydrated Kombu into 2cm pieces. In a small saucepan, combine 50g of the prepared dashi, Koikuchi soy sauce, Mirin, and 0.5g Salt. Add the sliced Dried Kombu and simmer over medium-low heat until the liquid is mostly absorbed and the Kombu is tender, about 10-15 minutes.