Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   1      thick         lemon slice
   1                    onion -- sliced
     1/4  cup           white vinegar
   1 1/2  teaspoons     salt
   1      tablespoon    prepared mustard
     1/2  teaspoon      pepper
   2      tablespoons   sugar
     1/4  teaspoon      cayenne -- (red) pepper
   2      tablespoons   butter
                        -----secondary ingredients-----
     1/2  cup           catsup
   2      tablespoons   Worcestershire sauce
   1      teaspoon      liquid smoke

Preparation:

Simmer first set of ingredients for 20 minutes, then add the secondary ingredients. Remove lemon slice and baste fish and Barbecue, basting with the sauce as needed.