To make brown sauce: Melt unsalted butter in medium saute pan. Add flour and cook over medium heat, stirring constantly, until mixture darkens, about 1 minute. Slowly add hot beef stock and stir until thickened, about 10 minutes. Mixture should be almost gelatinous. Set aside.

Coat each piece of meat with about 1 1/2 teaspoons pepper. Heat clarified butter in a large saute pan until very hot and almost smoking. Add meat and cook to desired doneness, turning once. (Time will depend on thickness of meat.) Carefully add 1 tablespoon brandy. Immediately flame, using long-handled match or butane fireplace lighter. Roll pan gently until flames subside. Remove meat from pan and keep warm. (If needed, cook meat in batches, flaming a second time with another tablespoon of brandy.)

Add mustard to cooking juices in pan and whisk over medium heat 30 to 45 seconds. Whisk in reserved brown sauce until incorporated. Add cream and cook over medium heat, whisking regularly, until sauce reduces by about one-third and thickly coats the back of a spoon; 5 to 10 minutes.

To serve: Set two pieces of meat on each of four plates and top with a portion of the sauce. Makes 4 servings.