Soak the dried mushroom beforehand for at least an hour but preferably overnight.
Put the potatoes in a pot and cover with water, add the mushrooms and the water in which they were soaked in.
Add a pinch of salt, pepper and caraway seeds.
Cook for around 20 minutes until the mushrooms and potatoes are soft.
Add the cream and thicken with the roux.
Season with vinegar, add the butter to mellow the flavor and add the chopped dill.
In a separate pan put some salt and a dash of vinegar and bring almost to a boil. Take a ladle and break an egg into it. Poach the egg in the ladle so the yolk remains soft and is encased in the egg white.
Serve each portion with the poached egg and a sprig of dill on top.
This soup is very hearty and could easily be served as meal on its own with your favorite bread.