Leek and potato soup

• 4 large leeks
• 1 medium onion
• 750 ml (1½ pints</

You will need a chopping board, a kitchen knife, a wooden spoon and a large saucepan with a lid. To purée the soup you will need a sieve or a vegetable mouli and a large mixing bowl, or an electric blender if there’s an adult around to switch it on and off for you.

Trim the green tops from the leeks down to about 2.5cm (1") from the white stem and cut away the roots. Slit the leeks leng