Heat gas or charcoal grill. In medium bowl, mix beef and taco seasoning mix. Shape mixture into 4 patties, about 3/4 inch thick.
Place patties on grill over medium heat. Cover grill; cook 13 to 15 minutes, turning once, until meat thermometer inserted in center of patties reads 160°F. Top each patty with cheese slice. Cook 1 to 2 minutes longer or until cheese begins to melt. Serve in buns with avocado and salsa. Top with chopped chile.