2Prepare Dashi Stock: In a small pot, combine 300g water and 5g kombu. Let the kombu soak for 30 minutes. Gently heat the pot over medium-low heat. Just before the water boils, remove the kombu. Bring the water to a boil, then add 10g katsuobushi. Immediately turn off the heat and let the katsuobushi steep for 5 minutes. Strain the dashi stock through a fine-mesh sieve, discarding the katsuobushi.