Brodo di Pesce

• bones of 1 large turbot including the head, halibut or monkfish
• 2 red onions, peeled and cut in quarters lengthways

Put the ingredients into a large saucepan, cover with about 2 litres (3.½ pints) cold water, and bring to the boil, skimming off the scum as it comes to the surface. Lower the heat and simmer gently for 15 minutes; in order to achieve a fresh-tasting stock, do not be tempted to do so for longer than this.

Strain and use immediately.