Peel and finely chop the onion. Heat the oil in a wide saucepan. Fry the chops in it in 2 portions on each side for about 2 minutes, remove. Sauté onion in the frying fat, add lentils and pour in broth.
Bring to the boil and cook for about 30 minutes. Clean, wash and finely dice the soup vegetables. Wash the marjoram, pluck the leaves from the stalks, except for something to garnish. Add the vegetables and marjoram to the lentils after about 15 minutes.
Place the cured pork on the lentils about 10 minutes before the end of the cooking time. Wash, halve and stone the plums. Cook for the last 5 minutes. Remove the meat. Season lentil vegetables with salt and pepper.
Peel and coarsely grate the horseradish. Arrange meat and vegetables on plates, garnish with marjoram and horseradish, sprinkle with pepper.