- 4 (4-ounce) pieces Spanish mackerel fillet, any bones removed
- 1 tablespoon fresh grapefruit juice
- 1 tablespoon fresh lime juice
- 2 tablespoons sake
- 3 tablespoons mirin (Japanese sweet rice wine)
- 3 tablespoons Japanese light soy sauce
- 1 tablespoon water
- 2 teaspoons sugar
- 2 teaspoons vegetable oil
- Garnish: lime slices
- Place fish in a flat-bottomed glass or ceramic dish just large enough to hold fillets in 1 layer. Stir together juices in a small bowl, then combine 1 tablespoon mixed juices with sake in another small bowl and pour over fillets. Marinate fish, covered, at room temperature, 10 minutes. Stir together mirin and 2 tablespoons soy sauce, then pour over fillets and marinate, covered, at room temperature, 5 minutes more (or in refrigerator up to 1 hour). Remove fish from marinade and pat dry. Discard marinade.
- Stir together water, sugar, and remaining tablespoon each mixed juices and soy sauce in a small bowl.
- Heat oil in a 12-inch heavy nonstick skillet over moderately high heat until hot but not smoking, then sauté fillets, skin side down, until just crisp and golden brown, 1 to 2 minutes. Turn fillets over and sauté until browned, about 1 minute more. Add soy mixture to skillet and cook, swirling skillet occasionally, until sauce is reduced to a glaze and fillets are just cooked through, about 3 minutes. (If sauce reduces before fish is cooked through, swirl in 1 additional tablespoon water, repeating as necessary until fish is done.)