1To prepare dashi, place the Kombu in 1500g Water in a large pot. Let it soak for at least 30 minutes, then heat over medium-low heat. Just before the Water boils, remove the Kombu. Bring the Water to a boil, turn off the heat, add the Katsuobushi, and let it steep for 5 minutes. Strain the dashi through a fine-mesh sieve, discarding the Katsuobushi.