Meanwhile, saute onions in fat until tender. Add sauerkraut and toss with a fork. Cook for 5 minutes, stirring occasionally. Add apples, peppercorns, and juniper berries. Pour in white wine. Cook slowly, covered, for 1 hour.
Meanwhile, fry sausages. Drain off fat and put sausages on absorbent paper. Add with meats to sauerkraut. Cook, covered, for 30 minutes longer. Discard peppercorns and juniper berries.