Miso Chilean Sea Bass

Steps

1. Start 1 to 2 days ahead. In a small saucepan, bring the sake and mirin to a boil and let it bubble for 30 seconds to cook off the alcohol. Off the heat, add the sugar and whisk until dissolved, then whisk in the white miso until you have a smooth, glossy paste with the consistency of thick cream. Let it cool completely.
2. Pat the toothfish fillets dry with paper towels and salt them evenly on all sides. Set them on a rack in the fridge for 20 minutes: fine beads of water appear on the surface. Blot them carefully.
3. Spread a thin layer of marinade in the bottom of a container just big enough for the fillets, lay the fish on top, and cover it with the rest, about 1/8 inch (3 mm) thick on every side. Press plastic wrap directly onto the surface, close, and marinate in the fridge for 24 to 48 hours, turning the fillets halfway through.
4. On the day, rinse the rice in cold water, rubbing it between your fingers, 4 or 5 times, until the water runs almost clear, then drain for 15 minutes. Put it in a heavy-bottomed saucepan with the 260 ml of water, bring to a boil, cover, turn the heat to the lowest setting, and cook for 12 minutes. Turn off the heat and let it steam for 10 minutes without lifting the lid.
5. Preheat the oven to 400°F (200°C) with a rack in the middle. Line a small baking sheet with foil and brush it with the oil. Take out the fillets and remove the marinade with your fingers, then with paper towels, without rubbing: only a barely visible film should remain. Set them on the sheet, skin side down if they have skin.
6. Bake for 10 to 12 minutes, until the flesh turns opaque on the sides and a thermometer reads about 120°F (50°C) in the center.
7. Switch the oven to broil on high and move the sheet to 4 inches (10 cm) below the element. Let it caramelize for 3 to 5 minutes, watching through the oven door: the surface should turn deep amber and glossy, with nearly black spots at the edges. Rotate the sheet if one side colors faster. The center should reach 140°F (60°C) and the flesh should separate into flakes under gentle pressure.
8. Meanwhile, toast the sesame seeds in a small dry skillet over medium heat for 2 minutes, until golden and starting to pop.
9. Fill two stoneware bowls with rice, set a toothfish fillet on each with a spatula without breaking it, sprinkle with the toasted sesame, and add a small mound of pickled ginger alongside. Serve right away.