Check fish for scales, season and set aside until needed. Make a stock with the fish head and bones plus 1/2 carrot, celery stalk, 2-3 parsley stalks, bay leaf, onion and water to barely cover. Bring to boil, skim, simmer 20 minutes, strain. (Or use chicken stock).

Preheat oven to 180C.

Remove feathery fennel tops to use as a garnish later. Cut bulbs into wedges. Drop into lightly salted simmering water and par-cook for 8-10 minutes. Drain. Smear the 2 tbsp butter over the base of a heavy-based ovenproof dish that will hold the fennel wedges snugly and that can be placed over a direct flame.

Place wedges in dish, dribble over the vinegar and then add stock to come halfway up the fennel pieces. Add the bay leaf and thyme. Cover and bake for about 20 minutes. Remove, uncover and transfer dish to top of stove to be finished later.

Heat the olive oil in a non-stick pan and cook the snapper fillets, skin side down. Hold them flat in the pan with an egg slice or similar for the first two minutes to prevent curling. Turn to cook the other side.

Bring to the boil a pan of lightly salted water and tip in the peas.

Place fennel in pan over moderate heat and reduce the cooking juices to a syrupy sauce. Drop in the peas and the reserved fennel tops. Taste and adjust seasoning.

To serve, spread fennel, peas and sauce onto hot serving plates. Top with fish fillets and maybe a piece of lemon.