1 lb. lean ground beef
2 tbsp. vinegar
2 tbsp. brown sugar
1/2 tsp. mustard
1/2 tsp. salt
1 med. chopped onion
1 c. ketchup

Combine onion and ground beef; brown on high in covered dish for 6 minutes; turn 1/2 way through cooking time. Drain. In medium bowl, combine vinegar, brown sugar, mustard, and salt. Cover browned beef with sauce and microwave 8 minute on 6 or until bubbly. Serve on buns or open faced.