Delicious melted cheesy tuna sandwiches.
Preheat oven to 350 degrees F (175 degrees C).
In a mixing bowl, combine sweet onion, drained tuna, mozzarella, and mayonnaise. Mix thoroughly.
Spread tuna mixture on slices of French bread to form a sandwich. Place sandwiches on a cookie sheet.
Bake in a preheated oven for 10 minutes.
Per Serving: 483 calories; protein 24.5g; carbohydrates 34.1g; fat 27.7g; cholesterol 41.1mg; sodium 716.4mg.