Combine the lettuce, tomatoes, cheddar and onions and mix well. Brown ground beef. You can add a little s&p and even a little hot sauce to flavor it. When meat has cooled add to lettuce mixture Crush up a handful of Doritos and add to your serving only (you can fridgerate the rest, and add more Doritos the next day, if they sit in the salad mixture they will get soggy)