Peel and wash the potatoes and carrot and cook them uncut in salted water for about 20 minutes. Take out carrot after 10 minutes and dice finely.
Heat the oil in a frying pan. Fry the sausages for about 10 minutes, turning them over.
Peel, quarter, core and cut apples into large pieces. Add to the potatoes about 5 minutes before the end of the cooking time and cook along with them.
Season the sauerkraut with salt, pepper and 1 pinch of sugar. Place the sausages on top of the sauerkraut. Fry the rest of the bacon in the pan until crispy, fry the carrot cubes briefly.
Wash the marjoram, shake dry and chop. Drain the potatoes. Add milk and butter, mash everything to a chunky puree. Season to taste with salt, nutmeg and marjoram. Serve the puree with sauerkraut and sausages and sprinkle with the bacon mixture.