Peel shallots and chop finely. Clean mushrooms and cut into thin slices. Cut meat into finger-thick strips. Heat clarified butter in a heavy skillet and cook meat, few pieces at a time, for about 3 minutes, stirring. Season with salt and pepper and remove from heat. Keep warm.
Heat butter in another pan and saute shallots and mushrooms until all liquid has evaporated. Add wine to the pan and bring to a boil. Add stock and cream and simmer, covered, for about 5 minutes. If desired, thicken sauce with cornstarch combined with a little water. Rinse parsley, shake dry and chop finely. Add meat to the sauce and simmer for 5 minutes. Arrange meat with sauce on plates and sprinkle with parsley. Serve with hash browns, if desired.