Good-Cooking - Lasagna Sandwiches

Ingredients

• 1/8 cup sour cream
• 1 tablespoon chopped onion
• 1/4 teaspoon oregano
• 4 slices Italian or other white bread
• 4 bacon strips, halved and cooked
• 4 slices tomato
• 2 (wide) slices Mozzarella cheese
• 2 tablespoons butter or margarine