1/4 cups minced green onions (or yellow onions)
    3 Tb butter
    Cook the onions slowly in the butter in a covered saucepan
    for 5 to 10 mins., until tender and transluscent but not browned.
     3-4 packed cups fresh watercress leaves & tender stems, washed & dried
     1/2 tsp salt
     Stir in the watercress & salt, cover, and cook slowly for about 5
     mins. or until leaves are tender & wilted.
     3 Tb flour
     Sprinkle in flour and stir over moderate heat for 3 mins.
     5-1/2 cups boiling white stock (or canned chicken broth)
     Off heat, beat in boiling stock. Simmer 5 mins., then purée
     through a food blender. Return to saucepan. If not served immediately,
     set aside uncovered. Reheat to simmer before proceeding.
     2 egg yolks
     1/2 cup whipping cream
     1-2 Tb softened butter
     Blend yolks and cream in mixing bowl. Beat a cupful hot soup into
     them by driblets. Gradually beat the rest of soup in thin stream.
     Return soup to saucepan and stir over moderate heat for 1-2
     mins. to poach yolks, but do not bring soup to simmer. Off heat, stir
     in enrichment butter a Tb at a time.
 f.  watercress leaves dropped for 1/2 min. in boiling water, refreshed
     in cold water, drained
     Pour soup into tureen or individual bowls and decorate with
     watercress leaves.
       If you want to serve soup cold, omit final butter enrichment and chill. 
       If you want to use sorrel or spinach, follow the same steps, but
       cut the leaves into thin slices (chiffonade) and do not purée the