In a large skillet, cook the beef, onion, celery, green pepper over medium heat until meat is no longer pink. Add garlic; cook 1 minute longer. Drain. Stir in the cheese, tomatoes, chili powder and cumin. Cook and stir over low heat until cheese is melted. Stir in corn chips.
Line six salad plates with lettuce; sprinkle with green onions. Top each with 1 cup beef mixture. Garnish with tomato wedges. Yield: 6 servings.