Himokawa Udon

Prepare the dashi: Gently wipe the kombu with a damp cloth. Do not wash or scrub. Place the kombu and 1000 grams of water in a pot and let it soak for at least 30 minutes, or preferably longer, at room temperature. Heat the pot over medium-low heat. Just before the water comes to a boil, remove the kombu. Bring the water to a boil, then turn off the heat. Add the katsuobushi to the hot water. Let it steep for 30 seconds, then strain the dashi through a fine-mesh sieve lined with a paper towel or cheesecloth. Discard the katsuobushi. You should have approximately 800 grams of dashi.

Prepare the broth (tsuyu): Return the strained dashi to the pot. Add 60 grams of koikuchi soy sauce, 30 grams of mirin, and 30 grams of sake. Bring the mixture to a gentle simmer over medium heat. Taste and add 2 grams of salt if needed to balance the flavor. Keep the broth warm over low heat.

Prepare the toppings: Thinly slice the scallions. Slice the kamaboko and narutomaki into decorative pieces.