GRILL DIRECTIONS: Heat grill. In medium bowl, combine ground beef and pesto sauce mix; mix well. Shape mixture into 8 thin patties, 4 inches in diameter. Place 2 tablespoons cheese on each of 4 patties to within 1/4 inch of edges. Top with remaining patties; pinch edges 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 patties are thoroughly cooked, turning once.
Meanwhile, place buns, cut side down, on grill. Cook 1 to 2 minutes or until buns are lightly toasted. Place lettuce, patties and tomato slices in buns.