Pat the hamachi kama dry with paper towels inside and out. Sprinkle each cheek evenly with kosher salt (about 1/4 tsp per piece) and a light dusting of freshly ground black pepper. Let rest uncovered in the refrigerator for 15–20 minutes to firm the flesh and dry the skin slightly — this helps achieve better browning.

Preheat and oil

Preheat the oven to 425°F (220°C). Heat an ovenproof skillet over medium-high heat. Add 2 tablespoons neutral oil and let it shimmer but not smoke.

Sear

Place the seasoned kama skin-side down in the hot skillet. Press gently for 10–15 seconds to ensure full contact. Sear 2–3 minutes until the skin is deeply golden and crisp. Flip carefully and sear the flesh side for 30–45 seconds to get light color.

Finish in oven

Add 1 tablespoon unsalted butter to the pan and spoon a little over the fish. Transfer the skillet to the preheated oven and roast for 6–9 minutes, depending on size (4 pieces: ~7 minutes). The flesh should be opaque, flake easily, and reach an internal temperature of about 135–140°F (57–60°C) for moistness. Remove from oven.

Rest

Let the kama rest on a warm plate for 2–3 minutes to allow juices to redistribute. Squeeze a lemon wedge over each piece just before serving if desired.

Ponzu Sauce & Garnish

Make ponzu sauce: In a small bowl whisk together 3/4 cup prepared ponzu, 1 teaspoon light soy sauce, 1 teaspoon mirin, 1 tablespoon fresh lemon juice, and 1 teaspoon grated fresh ginger until combined. Taste and adjust: add a bit more ponzu for acidity or 1/2 teaspoon sugar if you prefer slightly rounded sweetness.

Plate and garnish: Spoon 1–2 tablespoons of the ponzu sauce onto each serving plate (or serve in a small dipping bowl). Place one hamachi kama piece on each plate on top of or beside the ponzu. Scatter 3/4–1 tablespoon thinly sliced scallions over the fish, add a small mound (about 2 tablespoons) of shredded daikon if using, and finish with a light sprinkle of toasted sesame seeds. Serve remaining lemon wedges on the side.

Serve: Serve immediately while the kama skin remains crisp. Provide extra ponzu at the table for dipping.