Using hands, lightly break Doritos^® tortilla chips into smaller pieces; set aside. Heat oil in large, non-stick skillet set over medium-high heat. Crumble in ground beef; cook for about 5 minutes or until browned. Add onion and garlic; cook for about 5 minutes or until softened.

Sprinkle taco seasoning over beef mixture; stir in 1.5 cups water and beans. Simmer for 7 to 10 minutes or until thickened. Remove from heat and stir in half of the broken Doritos^® chips.

Meanwhile, divide lettuce among six shallow bowls. Top with beef mixture, tomatoes, avocado, radishes and remaining Doritos^® chips. Drizzle with dressing and sprinkle with green onions.