Preparation Melt 1 tablespoon butter in heavy large skillet over medium-high heat. Sprinkle both sides of steaks with salt and generous amount of ground black pepper. Add to skillet and cook to desired doneness, about 4 minutes per side for medium. Transfer steaks to 4 plates. Tent with foil. Melt 1 tablespoon butter in same skillet over medium-high heat. Add shallots; sauté 1 minute. Add wine, capers, and mustard; simmer until slightly thickened, about 2 minutes. Stir in parsley. Reduce heat to medium-low. Whisk in remaining 2 tablespoons butter. Season sauce with salt and pepper. Spoon over steaks.
Preparation Melt 1 tablespoon butter in heavy large skillet over medium-high heat. Sprinkle both sides of steaks with salt and generous amount of ground black pepper. Add to skillet and cook to desired doneness, about 4 minutes per side for medium. Transfer steaks to 4 plates. Tent with foil. Melt 1 tablespoon butter in same skillet over medium-high heat. Add shallots; sauté 1 minute. Add wine, capers, and mustard; simmer until slightly thickened, about 2 minutes. Stir in parsley. Reduce heat to medium-low. Whisk in remaining 2 tablespoons butter. Season sauce with salt and pepper. Spoon over steaks.