Sauté onions and garlic in a little butter. Add mushrooms, sweat briefly, add whipped cream/milk and cook a little. In a second frying pan, fry fillet pieces ( cut into approx. 2 cm cubes ), s+p, roast on high temperature for approx. 3 min. Add mushroom sauce, season with pepper and maybe a little soy sauce, sprinkle with parsley.
Serve with ribbon noodles and green leaf salad.