1/2 cup golden raisins
1 1/4 cups dry white wine, such as sauvignon blanc, divided
1 4-pound skin-on side of white fish (or whole fish, head and center bone removed), such as cod, halibut or Atlantic sea bass
Kosher salt and freshly ground black pepper, to taste
Juice of 1/2 medium lemon (at least 2 tablespoons)
1 1/2 medium lemons, cut into thin slices
3 tablespoons olive oil
1 large onion, halved then cut into very thin slices (about 2 1/2 cups)
2 large carrots, peeled, trimmed and cut into small dice
2 ribs celery, cut into small dice
1 (28-ounce) can chopped or diced tomatoes, plus their juices
Chopped flat-leaf parsley, for garnish
Preheat oven to 375 F.
Combine the raisins and 1/4 cup of the wine in a small bowl. Let sit for 15 minutes so raisins plump up, then drain.
Season the fish inside and out with the salt and pepper to taste; sprinkle with the lemon juice inside and out. Arrange about 8 lemon slices inside fish. Use long wooden toothpicks to seal fish closed.
Heat the oil in a large roasting pan or fish poacher over medium heat until oil shimmers. (You may need to do this over 2 burners.) Add the onion, carrots and celery; cook, stirring, for about 5 minutes, then add the tomatoes and their juices, raisins and remaining 1 cup wine, mixing well. Season with salt and pepper to taste.
Place white fish on top of sauce, spooning some sauce over fish. Increase heat to medium-high and bring to a boil, then cover and transfer to oven. Bake for 20 to 30 minutes, until fish flakes easily yet is moist and cooked through.
Transfer to a large platter to serve, spooning sauce over fish (remove skin, if desired). Garnish with remaining lemon slices and the parsley. Serve hot.
Makes 8 servings.