In a large heavy soup pot, melt the butter over medium high heat. Season the pork shoulder with salt and pepper and brown on all sides, about 15 minutes total.
Remove from the pan and set aside. Add the bacon, onions, juniper berries and caraway seeds and cook until the onions are soft and the bacon just beings to turn light golden, 10 minutes. Add the wine, chicken stock, sauerkraut, cabbage, and pork and cook covered, stirring occasionally, 1 ½ hours. Add the sausage and cook for 10 minutes, add the potatoes and continue to cook until the potatoes are cooked and the pork shoulder is fork tender, 30 minutes.
Place in a serving bowl or directly from the pan. Serve with a variety of mustards alongside.