Prepare the Daikon: Peel the daikon radish thickly and cut it into 1-inch rounds. To ensure it absorbs the broth perfectly, parboil the daikon rounds in water for 15 minutes until slightly soft and translucent. Drain well.

Clean the Fish: To remove any fishy smell, place the yellowtail pieces in a colander and pour boiling water heavily over them for 5 seconds. Instantly rinse them under cold running water, scraping off any blood clots or scales.

Build the Broth: In a wide, shallow pot, combine the dashi stock, soy sauce, sake, mirin, sugar, and half of the julienned ginger. Bring to a vigorous boil.

Simmer and Glaze: Gently add the parboiled daikon and the cleaned yellowtail to the boiling broth. Lower the heat to medium-low, cover with a drop lid (Otoshibuta), and simmer gently for 30 to 40 minutes. The daikon will turn deeply brown and the liquid will reduce into a thick glaze.

Rest and Serve: Turn off the heat and let the dish rest in the pot for 30 minutes (crucial, as the flavors penetrate deepest as it cools). Reheat gently, garnish with the remaining fresh ginger, and serve.