Brown ground beef and onion in skillet. Add beans and taco seasoning. Cover and simmer 10 minutes.
Combine lettuce, cheese, dressing, chips, avocado and tomatoes. Reserve a few chips, avocado and tomatoes for garnish. Add beef mixture and toss lightly.
Place in serving bowl and garnish with the reserved chips on top.
Note: you can also make it for 3-4 servings using half of the ingredients.