Watercress and Orange Soup

1 large onion, chopped
1 tablespoon olive oil
2 bunches or bags of watercress
grated peel and juice of 1 large orange
21/2 cups vegetable stock
2/3 cup light cream
2 teaspoons cornstarch
salt and freshly ground black pepper
a little heavy cream or plain yogurt,
to garnish
4 orange wedges, to serve


Soften the onion in the oil in a large pan. Add tqe watercress, unchopped, to the onion. Cover and cook for about 5 minutes until the watercress is soft.
Add the orange peel and juice and the stock to the watercress mixture. Bring to a boil, cover, and simmer for 10 to 15 minutes.
Puree the soup in a blender or food processor thoroughly, and strain if you want a smoother texture. Blend the cream with the cornstarch until no lumps remain. Stir into the soup, stirring until blended. Season to taste.
Slowly return the soup to a boil, stirring until just lightly thickened. Check the seasoning.
Serve the soup with a swirl of cream or yogurt, and a wedge of orange to squeeze in at the last moment.
If serving the soup chilled, thicken as above and leave to cool, before chilling in the refrigerator. Garnish with cream or yogurt and orange, as above.
Serves 4.