1 pound sturgeon fillet, cut into 2 pieces
1 teaspoon minced garlic
1/2 cup sliced onion
1 teaspoon fresh chopped rosemary
1/4 cup dry-cured or brine-cured olives, pitted
3 teaspoons capers
1/4 cup dry white wine
1/2 to 3/4 cup fresh tomato sauce (or a very good canned one)
1 tablespoon olive oil