Heat the clarified butter and fry the steak in it for 1 - 2 minutes on each side. Season with salt and pepper and place in an ovenproof dish in the preheated oven. Continue cooking at 175 ° C for approx. 8 - 10 minutes.
In the meantime, fry the mushrooms and shallot in the frying fat. Add crème fraîche and stir well. Serve with the steak.