Green Garden Soup

• 2 tablespoons butter or good oil
• 1 bunch watercress
• ½

Chop or grind [I think every kitchen should have a good mortar-and-pestle. My own is wooden, but I would like a stone one someday.] the vegetables (clean, of course). Heat them gently for about 10 minutes with the oil, and add broth. Cover and simmer slowly until very tender, about 45 minutes. Beat egg yolk and cream together, and add after the soup is in the tureen. Sprinkle with freshly groun