Heat a large skillet over medium-high heat.
Add the ground beef and chopped onion.
Cook for 5–7 minutes, stirring occasionally, until the beef is browned and the onion is soft.
Drain any excess grease.
Reduce the heat to medium.
Stir in the ketchup, vinegar, brown sugar, yellow mustard, salt, and pepper.
Simmer the Pennsylvania Coal Region Barbecue mixture for about 15 minutes, stirring occasionally until slightly thickened.
Spoon the hot beef mixture onto hamburger buns.
Serve immediately with chips, fries, coleslaw, or pickles.