Soak boletus in warm water. Dice the potatoes (1cm), cut
onion, bacon, carrots and celerie into small cubes. Heat oil in a large
pot; fry the onion, bacon, carrots and celery slowly until translucent.
Add the flour, sauteé lightly, add beef broth, and blend until smooth.
Season with salt, pepper, marjoram, caraway seed, crushed garlic,
chopped parsley, celery leaves and bay leaf. Remove boletus from the
soaking liquid, chop coarsely and add to the soup. Strain mushroom
soaking liquid through a kitchen cloth and add to the soup. Cook for
approximately 15 minutes, then add the potatoes and cook until they are
soft. Stir in the sour cream, remove from the hotplate and season with
salt, pepper and vinegar.