For every 1kg (2lb) offish trimmings use about 1litre (1¾pints) water and 300ml (½pint) white wine and include a carrot and an onion, both chopped roughly, a generous bundle of fresh herbs (parsley and bay leaf, and fennel is particularly good, too), 2-3tablespoons of lemon juice, 2teaspoons caster sugar and 10–12 black peppercorns. Do not use any trimmings from oily fish. Makes about 1.2litres (2pints).
Place all the fish trimmings in a large stockpot or saucepan with the chopped carrot, onion, bundle of herbs, lemon juice, sugar and black peppercorns.
Add the water and wine to the pan, bring to the boil, then simmer gently for 20-25 minutes, skimming the surface as necessary with a large spoon.
Strain the stock through a sieve lined with damp muslin. Use the stock at once or cool and then chill. Keep for up to 2 days in the refrigerator in a covered container.