GRILL DIRECTIONS: Heat grill. In medium bowl, combine ground beef, salsa and bread crumbs; mix well. Shape mixture into 12 patties, each about 4 inches in diameter and 1/4 inch thick. Sprinkle rounded tablespoon cheese in center of 6 patties, spreading slightly. Top with remaining patties; press edges together firmly to seal.
When ready to grill, place patties on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 11 to 13 minutes or until thoroughly cooked, turning once.
Place burgers on bottom halves of buns. Top each with tomato and avocado slice and 1 tablespoon sour cream. If desired, top with additional salsa. Cover with top halves of buns.