Brown the beef in a skillet over medium heat. Drain any excess grease.
Stir in the taco seasoning and ¼ cup of water. Reduce to a simmer for 10 minutes, stirring occasionally.
Remove from the heat and let cool. Cover and place in the icebox for 30 minutes or until chilled.
Mix the beef, beans, onion and tomatoes together in a large bowl. Stir in the lettuce and cheese. Stir in the dressing, to taste.
Sprinkle with additional cheese and generously top with the crushed Doritos or corn chips. Serve immediately.