Vegetable Stock

• 3 medium onions, peeled and chopped
• 1 small head celery, chopped
• 3 leeks, trimmed,

Put all the ingredients into a pot and cover with cold water. Bring it to the boil, skim off any scum that forms and simmer for 30-40 minutes. Strain through a fine-meshed sieve. Check its strength and reduce if necessary.