Peel and wash the potatoes and cut them into cubes of about 1 cm. Clean, wash and cut the leek into rings. Peel carrots, halve lengthwise and cut into thick slices. Peel and roughly dice the onion. Cut sausage into thin slices.
Fry the sausage slices in a wide pan for approx. 3 minutes, turning. Take out and drain on kitchen paper. Add oil to the frying fat, fry potatoes, carrots and onion for about 2 minutes, turning them over. Add stock, season with salt and pepper. Cook on low heat for about 20 minutes.
Wash the marjoram, shake dry and scrape the leaves off the stalks. Chop about half of it finely and add to the soup with leek. Let simmer for another 10 minutes. Pour cream into the soup. Season soup with salt and pepper, paprika and nutmeg and arrange in a deep bowl. Add slices of sausage and remaining marjoram to the soup.