Cut the beef steak across the grain into thin strips. Finely dice the onion; trim and slice the mushrooms.
Heat the clarified butter in a large frying pan until very hot. Sear the beef strips in batches, briefly, over a high heat, then take them out of the pan and set aside.
Fry the onion and mushrooms well in the pan fat until golden brown. Deglaze with the beef stock and let the liquid reduce briefly.
Stir in the crème fraîche and lower the heat. Return the seared meat and its juices to the pan and let it sit in the warm sauce.
Season to taste with salt and plenty of pepper. Stir the parsley through or scatter it over the top.
Serve straight away, while the meat is tender and the sauce nice and creamy.
Good to know
A dish like this is on the table quickly but still tastes like something special. Lovely and tender, creamy and just right for a warm, uncomplicated meal.
Contains milk (crème fraîche, clarified butter) and, depending on the stock, possibly other allergens such as celery – check the label; good for children if the meat is cooked right through, and in pregnancy, too, only eat it thoroughly cooked.