Kidney and Pickle Soup

Ingredients

 * 1 pound veal or beef kidneys, or 1 pound chicken giblets
 * 1 carrot
 * 1 parsley root
 * 2 ounces celery root
 * 1 onion
 * 1 teaspoon salt plus additional salt to taste
 * 6 whole black peppercorns, tied in a cheesecloth bag with 2 bay leaves
 * 3 potatoes
 * 3 tablespoons long-grain rice
 * 3 delicatessen sour pickles, coarsely grated
 * 6 teaspoons sour cream
 * 1 tablespoon finely chopped fresh tarragon or parsley

Directions

 * 1) To prepare the kidneys, remove their fat and membrane, cut in half, cover with cold water, and let soak for 6 hours, changing the water every 2 hours.
 * 2) Discard the last water. While the kidneys are soaking, cut the carrot, parsley and celery roots, and onion into julienne strips. In a 4-quart pot, bring 2 quarts of water to a boil.
 * 3) Add the kidneys (or the giblets, if you are using them), julienned vegetables, 1 teaspoon salt, and the peppercorns and bay leaves, and bring to a boil again.
 * 4) Lower the heat and simmer, partially covered, for 30 minutes.
 * 5) Meanwhile, peel the potatoes and cut into 1- inch cubes.
 * 6) Strain the stock, discarding the vegetables.
 * 7) Cut the kidneys into Y4-inch slices and return to the stock, adding the potatoes and rice.
 * 8) Cook slowly, partially covered, for 20 minutes, then add the pickles and simmer 5 minutes more.
 * 9) Turn off the heat, cover completely, and allow the flavors to mingle for 5 minutes.
 * 10) Blend the sour cream with 1 cup of soup and stir it back into the pot, then taste for seasoning.
 * 11) Serve in a warmed tureen, sprinkled with tarragon.