Pre heat the oven to gas mark 4, 350°F (180°C).

Wash the mackerel and pat dry with kitchen paper. Place them snugly in a baking dish and scatter over the onion rings, bay leaves and peppercorns.

Pour the wine vinegar and water over the mackerel, cover the baking dish with a lid or aluminium foil and bake for 30 to 45 minutes, depending on the thickness of the dish and the size of the fish.

When the fish are cooked, allow them to cool, then carefully lift them out using two spatulas so that they drain as you transfer them to a large plate.

Cut the head and tail off each one and lift off the top fillet. Now remove the backbone, which will come away very easily exposing the other fillet.

Arrange the lettuce and radishes on a platter and lay the soused mackerel, skin side up, along the centre.

Garnish with your chosen leaves.