Potato soup

4 medium potatoes, peeled and halved
1 carrot
1 parsley root
2 ounces celery root
1 teaspoon salt
1 bay leaf
6 black peppercorns
6 slices bacon, cut into l-inch pieces
1 large onion, cut into julienne strips
1 cup Polish smoked sausage, diced

Place the first 7 ingredients in a 4- to 5-quart pot, add 2 quarts of water, and bring to a boil. Lower the heat and simmer, partially covered, until the potatoes are tender, about 25-30 minutes. Strain and reserve the stock. Remove the potatoes and discard the other vegetables and the spices. Mash 2 potato halves thoroughly and cut the other 6 into 3/4-inch cubes. In a skillet, saute the bacon slowly until golden, remove from the pan with a slotted spoon, and let drain on paper toweling. Saute the onion in the bacon fat until golden, add the sausage, and saute for 3 minutes more, stirring continuously. Bring the potato stock to a boil, add the mashed and diced potatoes, the bacon, and the onion and sausage mixture, together with any fat remaining in the skillet. Remove from heat, cover, and let stand 5-10 minutes. Serve with black bread.