Prepare the base: place about 6 cups of Water and a 4–6 inch piece of Dried Kombu in a medium pot; let soak 30 minutes if you have time (or 10 minutes if short on time). Heat slowly over medium until just before it reaches a boil, then remove the kombu.
Make the dashi: after removing the kombu, bring the liquid to a gentle simmer and add a generous handful (about 1 cup) of Katsuobushi. Simmer for 30 seconds, turn off the heat, let the flakes settle for 2–3 minutes, then strain the broth through a fine mesh sieve or cheesecloth into a clean pot.
Season the broth: return the strained dashi to low heat and season it with Usukuchi Soy Sauce (about 2 tablespoons), Mirin (about 1 tablespoon) and Salt (about 1/2 teaspoon). Taste and adjust—add more soy or salt for saltiness, or a splash more mirin for sweetness.
Cook the noodles: bring a separate pot of water to a boil and cook the Udon Noodles according to package directions (usually 1–3 minutes for fresh or frozen, longer for dried). Drain and briefly rinse under hot water if desired to remove excess starch.
Assemble bowls: divide the cooked noodles into serving bowls and ladle the hot seasoned broth over them so the noodles are completely covered.
Garnish and finish: top each bowl with sliced Scallion, a couple slices of Kamaboko, a sprinkle of Tenkasu for crunch, and a light dusting of Shichimi Togarashi to taste.
Serve immediately while hot. Adjust seasoning at the table if needed and enjoy.
