Cold Cream of Watercress

[seirish]

INGREDIENTS:
4 bunches of watercress
1 quart vegetable stock
3/4 stick (6 tbsp.) butter
1 Spanish onion, thinly sliced
1/3 cup flour
1 quart milk
salt and white pepper to taste
1 cup heavy cream, chilled

DIRECTIONS:
1. Remove the leaves from the stems of the watercress, reserving 16 leaves for garnish. Bring the stock to a boil in a saucepan and add the stems. Reduce the stock by about half and strain the stock into a bowl.
2. Melt the butter in a large saucepan over moderate heat, and add the onion. Cook the onion until transparent, about 5 mintues, and add the flour. Stir well and cook for 2 minutes. Gradually add the milk and bring to a boil. Add the watercress leaves, and cook for 2 minutes. (Do not let the watercress darken.)
3. Pour the mixture into a food processor and puree, adding the strained stock. Strain the soup through a fine strainer into a bowl that is sitting over a bowl of ice. Season with the salt and white pepper. Chill in refrigerator until ready to serve.
4. Divide among 6 to 8 bowls. Whip the cream and add a dollop to the center of each soup serving. Garnish with reserved watercress leaves.