Heat oven to 350 degrees. Cook beef in 10-inch skillet over medium heat 8 to 10 minutes, stirring occasionally, until brown; drain. Stir in the beans and salsa. Heat to boiling, stirring occasionally.
Place broken tortilla chips in ungreased 2-quart casserole. Top with beef mixture. Spread with sour cream. Sprinkle with onions, tomato and cheese. Bake uncovered 20 to 30 minutes or until hot and bubbly. Arrange more tortilla chips around edge of casserole. Serve with lettuce and salsa.