Bratwurst is typically made from pork or veal and is popular throughout Germany. There are many regional variations, such as the Nürnberger Bratwurst, which is small and thin, or the Thüringer Bratwurst, which is longer and seasoned with marjoram.
Peel and chop the potatoes, place them in a pot with salted water and boil until tender (about 20 minutes).
Meanwhile, in a saucepan over medium heat, fry the diced bacon. Add the sliced onion and cook until softened. Add the sauerkraut, white wine, bay leaf, and juniper berries. Cover and let simmer for about 20 minutes.
While the side dishes are cooking, heat oil or lard in a frying pan. Cook the Bratwurst sausages on all sides over medium heat until they are evenly browned and cooked through (about 10-15 minutes). Be careful not to let the skin burst.
Drain the potatoes, add the butter and milk, and mash until smooth. Season with salt and white pepper to taste.
Remove the bay leaf and juniper berries from the sauerkraut. Place a scoop of sauerkraut, mashed potatoes, and two Bratwurst sausages on each plate. Serve hot with German mustard.