Wash the fish and sprinkle with lemon juice.

Cut the onion into rings and slice the 1/2 lemon.

Bring the water to the boil in a saucepan, together with the vinegar, salt, the onion rings, lemon slices, bay leaf and peppercorns and boil for 10 minutes. Add the fish cutlets and cook them for about 10 minutes, reducing the heat to prevent the stock boiling.

Peel, deseed and dice the tomato. Heat or cook the mixed vegetables and arrange them in a warm bowl. Lift the cutlets out of the pan, place them on top of the vegetables and keep the bowl warm in a low oven.

Dissolve the cornflour in a little water. Strain 250 ml (8 fl oz) of the fish stock into a small saucepan, then stir in the dissolved cornflour. Bring to the boil once.

Stir in the diced tomato, cream and herbs to make the sauce and season to taste with a little sugar and salt.