Carefully clean the mushrooms and cut them into slices.
Cut the pork tenderloin into thin slices and fry briefly; salt, pepper and remove from the pan.
In the same pan with a little butter, fry the onions and diced ham until translucent. Fry the mushrooms for five minutes, then deglaze with the cream and crème fraîche. Add the parsley, salt, pepper and simmer for ten minutes. Add the fried pork fillet slices and let everything stand for five minutes.