Coat the grill rack with cooking spray and pre-heat.
Combine the beef, salt and pepper; form into four balls. Indent the center of each ball and fill with 2 tablespoons of the cheese. Fold sides up and over to enclose cheese and form into 4-inch patties.
Grill patties 4-5 minutes per side or to desired degree of doneness. Place a burger on the bottom half of each roll; top with avocado slices and salsa and serve immediately.
Makes 4 servings
Nutritional analysis per serving: 418 calories, 30 g protein, 28 g carbohydrates, 4 g fiber, 22 g fat, 9 g saturated fat, 780 mg sodium