Cut the pork tenderloin into medallions. Season medallions with salt and pepper, turn in flour and fry briefly on both sides in hot fat, remove and set aside. Sauté the onions in the pan with butter, add the garlic, bay leaf, a little grated nutmeg, salt and pepper. Add the creme fraiche and cream to the onions, stir (do not boil) and season to taste. Place the pork fillets in an ovenproof dish and baste generously with the onion sauce. Cover the tin and stew it in the oven at 175 ° C for about 20 minutes. Arrange on preheated plates and sprinkle with parsley.