In a large pot with a thick bottom, heat the clarified butter, add the finely chopped onion and peeled, small-diced vegetables: parsnip, celeriac and potatoes. Fry over low heat until the onion is golden brown.

Pour the broth into the pot and add a pinch of marjoram. Cook over low heat until the vegetables are tender.

In a small bowl or jar, mix 2 tablespoons of sour cream with a small amount of warm soup. Then pour the mixture into the pot with the soup and mix. Lastly, add 2-3 tablespoons of grated horseradish and season with salt to taste.