Or is it Leek and Potato Soup? Or is it Vichyssoise?
Bring the leeks, potatoes and water to the boil in a 3 quart heavy-bottomed saucepan. Salt lightly, cover partially, and simmer 20-30 minutes, or until the vegetables are tender.
Purée the soup if you wish. Taste, and correct seasoning. After chilling the soup, you may wish to stir in a little more cream. Taste carefully again, and correct the seasoning. Top each serving with a sprinkle of chives or parsley.