Sloppy Joes

1 lb. ground beef
1/2 c. chopped onion
1/2 c. ketchup
1/2 c. water
1 T. vinegar
1/2 t. chili powder
1 T. mustard
1/2 t. salt
1/4 t. pepper
1-2 T. flour

Brown meat and onion.  Add ketchup, water, vinegar, chili powder, mustard, salt, pepper and flour.  Simmer together 10 minutes.