Tuna Steaks Provencal

Name: Tuna Steaks Provencal
Ingredients: 1 tablespoon extra-virgin olive oil, divided; 1 red bell pepper, chopped; 1 yellow bell pepper, chopped; 1 small red onion, sliced; 2 cloves garlic, minced; 2 tomatoes, peeled, seeded and chopped (see Tip); ¼ cup fish stock or water; 2 tablespoons dry red wine; 2 tablespoons sliced, pitted, good-quality black olives; 1 1/2 teaspoons chopped fresh rosemary, or 1/2 teaspoon dried; Salt & freshly ground pepper, to taste; 4 4-ounce tuna steaks, (about 1 inch thick)