Preheat oven to 350° F.
Mix crab, mayonnaise, onion, lettuce, salt and lemon juice. Place a tomato slice on each muffin half. Arrange crab salad on top of tomato, dividing equally among sandwiches. Top each with a slice of mozzarella.
Transfer to a baking sheet and bake for 15 to 20 minutes, or until cheese is lightly browned.Makes 6 Source: