1Prepare dashi: Gently wipe the kombu with a damp cloth. Place kombu and 1200g water in a large pot and heat over medium-low heat. Just before the water reaches a boil (when small bubbles appear along the edges), remove the kombu. Bring the water to a full boil, then turn off the heat and add katsuobushi. Let it steep for 30 seconds, then strain the dashi through a fine-mesh sieve into a clean pot, discarding the katsuobushi.
2Prepare vegetables: Peel the daikon radish and cut into 1.5 cm thick half-moon slices. Peel the carrot and cut into 1 cm thick rounds or half-moon slices. Peel the potato and cut into large, bite-sized chunks. Slice the scallions thinly for garnish.
