Aunt Arlene's Barbecue Beef

1 tablespoon butter or margarine

1 tablespoon flour

1 teaspoon dry mustard

1/2 teaspoon salt

1 1/4 pounds ground beef

1/2 large onion, chopped

1/8 cup sugar

3/4 cup hot water

3/4 cup ketchup

1/8 cup Worcestershire sauce

Brown ground beef and onion; remove.  Melt butter or margarine and stir in flour until smooth.  Add water first and stir well.  Add other ingredients.  Simmer 45 minutes.