Slice the pork into pieces approximately 7mm thick.
Brown the pork in a hot oiled frying pan and set aside to keep warm.
Cook the chopped onions in butter until soft and golden.
Deglaze the pan with wine, add chicken stock, and boil to reduce by 25%.
Sauté the sliced mushrooms in butter and oil and add them to the pork.
Stir cream into the sauce, bring to a boil, and thicken with roux.
Combine the pork, mushrooms, and any meat juices into the sauce.
Simmer with lemon juice for two minutes and stir in most of the parsley.
Serve in hot dishes garnished with parsley-dipped croutons.