Cream of Potato, Leek and Onion Soup with Buttered Onions

Soups made with the combination of leek, onion and potato, as this one is, can’t fail to be delicious, whatever the proportions and final finish. In this version, when almost equal quantities of potato, leek and onion are simmered until soft and then puréed, the leeks give the soup a silky and creamy finish. The addition of buttery strands of soft onion stirred into the soup just before serving adds a surprising ‘garnish’.