Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
2         small         fresh mackeral
1         large         grapefruit, green
1         small         sweet onion, very finely chopped
                        Gin
2         teaspoons     soft brown sugar
2         oz            butter
                        Orange juice
                        Potato starch

Preparation:

Clean the mackeral. Zest the grapefruit, then juice it. Reserve 4 thin slices of peel. Add an equal quantity of gin to the juice and zest. Marinade the fish in this mixture for a couple of hours. Remove the fish from the marinade, and grill for about 5-8 minutes each side, depending on the size of the fish. (Until the flesh next to the bone is just opaque.) Meanwhile fry the onion in the butter on a low heat until just golden. Add the marinade and sugar, and turn the heat up - simmer the sauce until it is thickish. Adjust seasoning, and thickness with orange juice / potato starch.