1. Pre-heat oven to 180C / 350F / Gas 4. 2. Place the mackerel in a shallow oven-proof dish. Place a bay leaf inside each fish. Sprinkle the Sugar over them and add the peppercorns. Add a little salt if you wish. 3. Mix the vinegar and the tea together. Pour over the mackerel. Cover the dish and bake for 45 minutes until cooked. 4. Chill well before serving the fish with a little of the marinade and bread.