Sauté the green pepper and garlic in margarine in a large saucepan until the green pepper is tender. Add flour, stirring until smooth. Cook for 1 minute, stirring constantly. Gradually add milk and seasoning to saucepan, cook over medium heat, stirring constantly, until mixture is thickened and bubbly. Stir in tomatoes, onions, and corn. Remove from heat. Spoon the mixture into a 2 quart casserole dish coated with cooking spray and bake at 350ºF. for 50 minutes. Makes 8 servings