Brining the fish in water with salt and sugar heightens its natural flavor, but it also provides a little added insurance that the fish will remain moist, even if it's slightly overcooked. Mackerel has a firm texture and full-bodied flavor, making it a perfect candidate for the grill.
1/2 cup dry white wine
1/4 cup raisins
1 cup extra-virgin olive oil, divided
4 (6-oz.) mackerel fillets, from 2 (1 1/2-lb.) whole fish
1 1/2 teaspoons kosher salt, divided
1 1/2 cups chopped red bell pepper
1 1/4 cups chopped red onion
1/4 cup pine nuts
3 tablespoons light brown sugar
1 cup diced eggplant
3/4 cup red wine vinegar
3 tablespoons chopped fresh flat-leaf parsley
1 French bread baguette, sliced
How to Make It
Combine the wine and raisins in a small bowl; let stand 10 minutes.
Meanwhile, heat 2 tablespoons of the oil in a large skillet over medium-high. Cut 3 shallow slits in the skin side of the fillets. Sprinkle fillets with 1 teaspoon salt. Add 2 fillets, skin sides down, to skillet, and cook until lightly browned, 3 to 4 minutes. Remove skillet from heat; turn fish. Let stand 3 minutes. Transfer cooked fillets to a 13- x 9-inch glass or ceramic baking dish. Discard oil from skillet. Repeat procedure with 2 tablespoons of the oil and remaining 2 fillets. Wipe skillet clean with paper towels.
Heat the remaining 3/4 cup oil in skillet over medium. Add the bell pepper, onion, and pine nuts to skillet, and cook, stirring occasionally, until vegetables are tender and pine nuts are lightly toasted, about 7 minutes. Stir in the brown sugar until dissolved. Add the eggplant; sauté 1 minute. Add raisin mixture, vinegar, and remaining 1/2 teaspoon salt to skillet, and cook until mixture is slightly syrupy, 5 to 7 minutes. Pour sauce mixture over fillets; cool to room temperature, about 1 hour. Sprinkle with parsley, and serve at room temperature with baguette slices. (Or cover and refrigerate fillets overnight, allowing the fish to come to room temperature before serving.)