Festive Beef Fillets

1 envelope brown gravy mix

1 jar {4 1/2 oz.} sliced mushrooms -- drained

2 teaspoons prepared horseradish

4 5 ounce beef tenderloin fillets

1/8 teaspoon pepper

Prepare gravy according to package directions; add mushrooms and horseradish. Set aside and keep warm. In a non-stick skillet, cook fillets over medium-high heat until meat reaches desired doneness {about 10 to 13 minutes for medium}, turning once. Season with pepper. Serve with the gravy.