1 lb. ground beef
1 each med. onion
1 c. BBQ sauce
2 tbsp. brown sugar
1 tsp. mustard
6 hamburger buns

Combine ground beef into 2 quart glass casserole; stir in onion. Cover with glass lid. Microwave for 5 minutes on high; drain fat. Stir in remaining ingredients, cover, microwave 5 to 6 minutes on low; let stand 5 minutes. Serve on hamburger buns.