Cream of Watercress Soup (Potage Creme de Cresson)
Source: Pines and Plantations/1976

5 to 6 green onion bulbs, minced
1/2 teaspoon salt
3 tablespoons flour
5 cups chicken broth, heated
2 egg yolks
handful of watercress leaves
3 tablespoons butter
4 packed cups fresh watercress leaves and tender stems, washed and dried in a towel (about 1/4 pound)
1/2 to 1 cup heavy cream

Combine the green onions, butter and 1/2 cup water in a heavy saucepan. Bring to a boil. Reduce heat and simmer until all the water has boiled away and the onions are tender and translucent. Stir in the watercress and salt.

Cover and cook over low heat for about five minutes or until the leaves are tender and wilted. Sprinkle in the flour and stir over moderate heat for three minutes. Stir in the hot broth, then simmer for five minutes.

Puree, about half at a time, in an electric blender. Pour back into the saucepan. Taste for seasoning. It may need salt and pepper. Combine the yolks and 1/2 cup of cream in a bowl. Beat with a whip until mixed.

Gradually beat a cupful of the hot soup into the mixture. Then combine with the soup in a thin, steady stream, beating constantly. Place over moderate heat for a couple of minutes. Do not bring to a boil.

Refrigerate until cold. If too thick, stir in more cream just before serving. Drip the watercress leaves into boiling water for half a minute, refresh in cold water and drain. Use as a garnish.