1To prepare dashi stock, place Water and Kombu in a medium pot. Let Kombu soak for 30 minutes. Heat the pot over medium heat, bringing it just to a simmer. Remove Kombu just before the water boils. Add Katsuobushi to the simmering water. Turn off the heat immediately and let Katsuobushi steep for 5 minutes. Strain the dashi stock through a fine-mesh sieve, discarding the solids.