In a bowl, combine the meat, breadcrumbs, egg, mustard, and spices. Season with salt and pepper.
With lightly oiled hands, shape each meatball with about 22.5 ml (1 1/2 tablespoons) of the meat mixture.
In a large non-stick skillet, brown the meatballs in half the oil. Set aside on a plate.
In the same skillet, brown the mushrooms, peppers, and onion in the remaining oil. Season with salt and pepper. Add the garlic and cook for 1 minute. Return the meatballs to the skillet and add the tomato sauce. Bring to a boil. Cover and simmer gently for about 10 minutes or until the meatballs are cooked through. Adjust the seasoning.
Slice the rolls open and toast them. On a plate, layer the cheese and lettuce in the rolls. Top with meatballs.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.