Zupa Grzybowa

Ingredients

 * 1/4 lb dried wild mushrooms
 * 9 cups beef stock or canned reduced-sodium beef broth
 * 1 cup butter
 * 1 cup finely chopped onion
 * 1 tablespoon cornstarch
 * salt
 * white pepper
 * sour cream
 * chopped fresh parsley

Directions
Cover mushrooms with cold water and soak overnight. Drain the mushrooms reserving the soaking liquid, strain the liquid through a fine cloth. Rinse the mushrooms in cold water to remove any remaining sand then slice into strips. Add the mushrooms, 8 cups of of the beef stock and the soaking liquid to a 3 quart saucepan, bring to a boil, reduce heat and simmer over low heat for 4 hours. Melt the butter in a heavy skillet, add the onion, saute until golden brown then add to the soup. Whisk the cornstarch with the remaining cup of beef stock, add to the soup, stir and simmer until slightly thickened. Season to taste with salt and pepper, ladle into individual bowls, top each with 1 tablespoons of sour cream and sprinkle with parsley.