Tempura Dipping Sauce (Tentsuyu)

Measure the dashi, mirin, and soy sauce into a small saucepan and stir briefly to combine. The ratio of dashi to mirin to soy at 4:1:1 is the classic tentsuyu proportion for standard deep-frying. This ratio produces a broth that is savory but light — the dashi does the heavy flavor lifting, the mirin sweetens and rounds, and the soy colors and deepens. Place over medium heat and bring to a gentle simmer, stirring once. Let it simmer for 2–3 minutes to burn off the raw mirin alcohol and meld the three components. The sauce should smell deeply of the sea (from the katsuobushi in the dashi), sweet rice wine, and a clean, balanced soy.

Peel a section of daikon and grate it on the finest setting of a Japanese oroshi grater (or the small holes of a box grater, or a Microplane) into a small bowl. Grate in gentle circular or back-and-forth strokes — pressing too hard will make the daikon watery and fibrous rather than fine and fluffy. Immediately gather the grated daikon with clean fingertips and press it into a small, clean hemisphere — the Japanese presentation always shows the daikon mounded neatly beside the sauce bowl, ready to stir in. The pungency of freshly grated daikon fades quickly — grate it immediately before serving, not ahead of time.

Ladle the hot tentsuyu into small individual dipping bowls — lacquerware or ceramic, ideally with a wide mouth that allows a full shrimp or vegetable piece to be dipped without splashing. Place the mound of grated daikon and a small amount of grated ginger on the rim or in a corner of a small condiment plate beside each bowl. The diner stirs the daikon and ginger into the hot tentsuyu themselves, controlling the intensity. To eat: dip a piece of hot tempura briefly into the broth — one to two seconds — so the batter absorbs a little broth without going soggy, and eat immediately. The salt, umami, and sweet of the broth complement the neutral crunch of the tempura batter.