Preheat the oven to 400 degrees F.
Lightly oil a baking dish that will accommodate the fish fillet. On a flat plate, stir together the flour with a little salt and pepper, then dredge the fish in the seasoned flour and shake off the excess.
In a saute pan, heat about 1 tablespoon oil, or as needed to form a film in the pan, over medium-high heat. Saute the fish on both sides until lightly colored. With a slotted spatula, remove the fish to the prepared baking dish.
In the same saute pan, heat 2 tablespoons olive oil over medium heat. Add the onion and celery and saute until soft and pale gold, about 10 minutes. Add the tomatoes, if using, and simmer for 3 minutes to thicken slightly. Add the olives, pine nuts, raisins, capers, garlic, and wine and simmer for 8 to 10 minutes to blend the flavors. Taste and adjust the seasoning.
Ladle the sauce over the fish. Bake until the fish tests done with the point of a knife, about 10 minutes. Eat while hot or warm.
Variation: You can also make this dish in a saute pan. Just place the sauteed fish in the sauce in the pan, cover, and simmer gently over low heat until the fish cooked through, about 10 minutes.
Recipe courtesy Solo Suppers, Chronicle Books, 2003