Melt butter in a large skillet over medium-high heat. Add fillets, and cook 6 minutes on each side or to desired degree of doneness. Remove fillets from skillet, and keep warm.
Add wine, broth, and peppercorns to skillet; cook 20 minutes or until liquid is reduced by half. Stir in cream and mustard; cook 20 minutes or until liquid is reduced by half. Return fillets to skillet, and serve warm.