Begin by gently wiping the surface of the kombu with a damp cloth—retain the white coating as it contains valuable umami compounds. Combine the kombu and water in a saucepan and heat slowly over medium-low. Just before the water reaches a boil, remove the kombu to prevent bitterness.

Once the water begins to boil, switch off the heat and sprinkle in the katsuobushi. Let it steep for 30 to 60 seconds, allowing the umami-rich essence to infuse the broth. Strain the mixture through a cheesecloth-lined sieve and discard the solids. This forms your aromatic base stock.

Ensure your kajika fish is cleaned thoroughly—scaled, gutted, and optionally scored across the skin for even heat penetration. To purify and refine the taste, blanch the fish briefly. Dip it into a pot of boiling water for 5 to 10 seconds, then immediately cool it in an ice bath. Once chilled, pat the fish dry with a paper towel.

Transfer the prepared dashi to a clean saucepan and add the sake. Warm the liquid over medium heat until it begins to simmer gently. Carefully lower the kajika fish into the pot and let it cook for approximately 5 to 7 minutes until the flesh becomes opaque and tender. Avoid vigorous boiling to preserve the clarity of the broth and integrity of the fish. Periodically skim off any surface impurities.

If using daikon and carrots, add them to the pot halfway through the fish’s cooking time or pre-simmer them in the broth before adding the fish to ensure they soften adequately.

Once the fish is cooked, gently remove it from the broth and set aside to prevent overcooking. Season the broth with soy sauce and salt, beginning conservatively and adjusting to your taste. The goal is to maintain a subtle, clean depth of flavor without overpowering saltiness.

Place a piece of fish into each serving bowl. Pour the hot, seasoned broth over the fish, ensuring the vegetables are evenly distributed. Garnish with a few slivers of fresh ginger and a scattering of mitsuba or sliced scallions for a vibrant, aromatic finish. Serve immediately, ideally accompanied by a bowl of steamed rice and complementary Japanese side dishes.