The only thing to say about this soup is that it is perfectly delicious; it is especially good cold, but then it is also especially good hot.
Adapted from Mastering the Art of French Cooking, Volume 2 by Julia Child (Alfred A. Knopf, 1970)
Peel the cucumbers. Cut 18-24 paper-thin slices and reserve in a bowl for later. Cut the rest of the cucumbers into ½-inch chunks; you will have about 4½ cups.
Cook the shallots slowly in the butter for several minutes until tender but not browned. Add the cucumber chunks, chicken broth, vinegar, and herbs. Bring to a boil, then stir in the farina. Simmer, partially covered, for 20-25 minutes. Purée in a blender and then return the soup to the pan. Thin out with the extra chicken stock if necessary, and season with salt and white pepper to taste.
Just before serving, beat in ½ cup of the sour cream. Ladle the soup into soup bowls and place a dollop of the leftover sour cream on top of each. Float slices of cucumber on top of the cream, and decorate with a sprinkling of herbs.