In a large skillet over medium heat, brown the ground beef & onion. When the beef's cooked. Drain the meat. Return the meat to the hot skillet and stir in the ketchup & mustard, until evenly combined.
In a large mixing bowl, add the cooled off ground beef mixture. Also add the cheese, tater tots, condensed soup, and sour cream. Stir just until evenly combined.
Spray a 9x13 baking dish with non stick cooking spray, then spread the mixture evenly out into the dish. Top with extra shredded cheese and bacon crumbs, if desired.
Bake the dish at 350 degrees for 45-50 minutes.
Spoon onto plates, and serve topped with relish, or pickles, and topped with fresh veggies.