Dab the meat dry and possibly cut it a little smaller. Peel and roughly dice the onions. Heat oil in a pot. Brown the meat all around. Add onions and season with salt, pepper and paprika.
Stir in the tomato paste. Deglaze with tomatoes. Add stock, bring to the boil and cook for about 1 hour. Quarter peppers, clean, wash and cut into pieces. Clean, wash and cut leek into rings.
Peel, wash and chop the potatoes. 30 minutes before the end of the cooking time, add the potatoes and peppers. Drain the sauerkraut and cook with the leek for the last 15 minutes. Season sauerkraut stew again and serve.