makes 1.8 litres/3pt ingredients

2.3kg/5lb fish trimmings

5 onions, quartered

5 celery sticks, including leaves,

chopped 5 sprigs of fresh flat-leaf parsley 5 bay leaves 1 teaspoon dried thyme 750ml/11/4pt dry white wine salt and freshly ground black pepper

• Put all the ingredients in a large stockpot or heavy saucepan, and add 3 litres/5pt water. Set over a high heat, bring to the boil, then skim off any scum from the surface.

• Reduce the heat and simmer, uncovered, for about 40 minutes, continuing to skim off scum from the surface as it rises. Carefully strain the liquor through a fine-mesh sieve, and discard the seasonings.

• Allow to cool, then refrigerate until needed. Use on the same day the stock is made, or divide into portions and freeze until needed.