Peel, wash and chop the potatoes and carrots. Cook both in salt water for about 25 minutes. Peel onions and cut into rings. Wash and dry the smoked pork loin. Heat the oil in a pan.
Fry the cured pork on each side for about 4 minutes. Remove the meat and keep warm. Add onions to the frying fat and fry. Dust with flour, deglaze with balsamic vinegar, add stock while stirring and bring to the boil.
Season to taste with mustard, salt, pepper and marjoram. Drain the potatoes and carrots and collect the vegetable water. Add 200 ml vegetable water and cream to the potatoes and mash them coarsely. Season to taste with salt, pepper and nutmeg.
Serve the carrot-potato puree, smoked pork and onion sauce together. Garnish with marjoram.