Chop the onion and the white of the leek and saute in butter in a large saucepan for 2-3 minutes. Peel and chop the potatoes. Roughly chop the leaves and tender stalks of the watercress. Add watercress, potatoes, and the stock to the saucepan. Bring to a boil and simmer for 45 minutes.

When done, liquidize, return the soup to the saucepan, season to taste with salt and pepper. Add the cream and cook for a further three minutes.

Makes 4 servings.

Source: A Taste of the Belgian Provinces, Enid Gordon and Midge Shirley (published by The Tuesday Group, rue Frans Merjay, 1060 Brussels).