22. Prepare dashi stock: Place Kombu in 600g Water and let soak for 30 minutes. Gently heat the Kombu water over medium heat. Just before it boils, remove the Kombu. Add Katsuobushi to the hot water, bring to a boil, then immediately turn off the heat. Let the Katsuobushi settle to the bottom, then strain the dashi stock through a fine-mesh sieve, discarding the Katsuobushi.