Season the filet medallions with sea salt and black pepper
Melt the butter in a large saute pan over medium-high heat.
Dredge the filet in flour
Add the beef and saute for about one minute on the first side, then turn over the beef and saute on the other side for about one minute.
Add the shallots and garlic to the side of the pan and saute briefly.
Add the mushrooms and continue to suate, stirring, until soft (about 2 minutes)
Remove the beef from the pan and place on a plate and cover to keep warm.
Remove the pan from the heat and add the Jack Daniels.
Light the alcohol with a grill lighter or simply saute for a minute to allow the alcohol to burn off.
Add the mustard and cream, mix thoroughly and cook, stirring, for 1 minute.
Add the beef stock and simmer for 1 minute.
Add the Worcestershire and stir to combine.
Thicken the sauce with a beurre manie (butter and flour)
Return the meat and any accumulated juices to the pan and turn the meat to coat with the sauce.
Divide meat between two plates, top with scallions and parsley and serve with your favorite side