In a large saucepan combine sweet pepper and onion; add water. Cover and cook over medium heat about 2 minutes or just until vegetables are crisp-tender; drain. Stir in thawed Marvelous Meatballs and pizza sauce. Heat through.
Cut the top 1/2 inch from rolls. Open and scoop out some of the soft bread inside the bottom part. Spoon 6 meatballs inside each roll; spoon the sauce and vegetables over meatballs. Sprinkle with cheese. Top with tops of rolls. Place sandwiches, top sides up, in a 2-quart rectangular baking pan. Bake in a 400 degree F oven for 10 to 15 minutes or until hot and crusty, and cheese is melted. Makes 4 servings.