In medium bowl, combine ground beef and chiles; mix well. Shape mixture into 4 patties, 1/2 inch thick.
Heat nonstick stove-top grill pan over medium-high heat until hot. Add patties; cook 2 minutes. Reduce heat to medium-low; cook an additional 6 to 10 minutes or until no longer pink in center, turning once. Top each patty with cheese; cook just until cheese is melted.
In small bowl, mash avocado with fork. Stir in mayonnaise until well blended. Spread bottom halves of buns with avocado mixture. Place patties on bottom halves. Top with taco sauce, lettuce, tomato and top halves of buns.