Melt butter or margarine. Add onion and green pepper and cook 2 minutes over low heat. Add tomatoes, tomato paste or chili sauce, and seasoning, and cook 10 minutes over low heat until sauce has thickened somewhat. Add shrimp, olives and sherry. Cover and let simmer over low heat 5 minutes. Add more salt, if needed. Serve with hot toast or heated French bread. Yield: 6 servings.