Cut the potatoes into small cubes and cook together with the bay leaves in the beef broth until soft.
Mix crème fraîche and sour cream with flour and a little boiling soup until smooth and slowly stir into the potato soup in circular motions with a whisk.
Continue to simmer until the soup becomes nice and creamy. Season to taste with caraway, nutmeg, vinegar, salt and pepper.
Preparation Tip:
A squeeze of lemon juice makes the sto soup more digestible and zingy.