Brown meat in skillet sprayed with non-stick spray over medium-high heat. Break up meat with spatula while cooking so you don't end up with huge chunks of meat. Add chopped onion when meat is about 1/2 way browned. Saute until onions are translucent. Drain excess fat if necessary.
Add catsup, brown sugar, mustard, chili powder, paprika, cumin, garlic powder, Worcestershire sauce and vinegar, Stir to coat meat. Add salt and pepper to taste. TASTE to make sure it's not too sweet or too tart.
Let simmer for a few minutes to combine flavors. Serve on buns with sliced cheese if desired.