Vegetable stock

• 3 onions, quartered
• 4 carrots, chopped
• 2 leeks, trimmed and chopped

Put all the ingredients in a large saucepan over a high heat and add 2l/70fl oz/8 cups cold water. Bring to the boil, then turn the heat down to low and simmer for 30 minutes.

Pour the contents of the saucepan into a plastic container, cool, then store in the fridge overnight.

Strain the stock and discard any solids. Store in an airtight container in the fridge for up to a week