To freeze and grill later, prepare Horseradish Butter as directed above; place into freezer container. Prepare marinade and steak as directed above. Place container and sealed freezer food bag into freezer; freeze up to 3 months. To thaw, place container and bag in refrigerator 24 hours or until thawed. Heat gas grill on medium-high or charcoal grill until coals are ash white. Remove steak from marinade; discard marinade. Place steak onto grill. Grill, turning once, 12-19 minutes or until internal temperature reaches 145°F (medium-rare) or desired doneness. Serve as directed above.