Yosenabe (Mixed Hot Pot)

To make dashi broth: Place Water and Kombu in a large pot. Heat over medium-low heat until just before boiling (small bubbles appear). Remove Kombu before it boils. Add Katsuobushi, bring to a gentle simmer, then turn off heat immediately. Let it steep for 5 minutes, then strain through a fine-mesh sieve. Discard Katsuobushi.