White Fish Stock

• 1 onion, peeled and chopped
• 1 bulb of fennel, chopped
• 1 leek, chop

To make the stock

Gently sweat the onion, fennel, leek and celery in the butter in a large saucepan until they are soft but not browned. Add the fish bones and white wine. Top up with 1.7 litres of cold water and bring gently to the boil, skimming off any scum that rises to the surface. A