This is also a very traditional Slovenian recipe. It is very simple, but it is important to be made with wild mushrooms, the best are porcini (ceps) and chanterelles. With button mushrooms it wont taste as it should. If you use dry porcinis, you have to soak them in a cold water for about two hours before starting to cook. This was the recipe I used whenever I wanted to introduce somebody to Slovenian cuisine while I was living abroad.
Put a pot of cold water on a stove and put in sliced mushrooms, potatoes (small cubes), crushed garlic, parsley, laurel, marjoram and bring everything to boil. In the meantime saute some chopped onion on oil or butter and when it is soft, add 1 – 2 spoons of flour. Mix well and add this to the soup. Adjust seasoning (salt, peppers) and simmer the soup for about 20 minutes or until potatoes are cooked. Serve with sour cream.