Heat butter and fry onion in it. Chop chanterelles or oyster mushrooms, chop ham and fry everything together. Bind with egg and flour and season with parsley. Beat the beef cutlets, season with salt and pepper and spread with mustard and anchovy paste. Spread the mushroom filling on the cutlets, fold in the edges, roll up and tie tightly. Heat the oil and brown the roulades all over. Add red wine and some water and cook until soft. Sauté chanterelles or mushrooms in butter, deglaze with the roast stock. Mix the sauce with crème fraîche, thicken with cornflour mixed with a little water. Put the roulades on plates and pour the ready mushroom sauce over them.