Mix all the relish ingredients together in a large bowl. Taste after 1 hour, and adjust the seasoning if necessary.
Strain the court-bouillon into a clean pan and bring to the boil. Drop in the cod fillet, bring back to the boil and switch off the heat. Leave for 10 minutes, then remove and skin the fish. Divide the relish between four plates, and carefully arrange the flakes of cod ove