Preheat skillet to 400 degrees F. Add enough clarified butter to just coat pan base. Season meat generously with salt and pepper and place into butter to sear on all sides, about 5 minutes per side.
Meanwhile, in a saucepan, heat 1 tablespoon clarified butter and add shallot and cook. Add brandy and cream. Lower heat and add mustard and lemon juice. Let sauce slowly reduce. Add fresh butter and strain sauce through fine sieve. Return sauce to clean pan on stove and keep warm.
Cut steak in 1/2-inch thick diagonal slices. Skim fat off pan residue and pour residue into sauce and mix in. Serve spooned over meat slices.
Recipe courtesy of La Sologne in Paris