Place a 10-inch cast-iron skillet on grill rack over hot coals (400° to 500°); let skillet heat at least 10 minutes or until very hot.
Prepare Orange-Balsamic Sauce; set aside, and keep warm.
Combine paprika and next 5 ingredients in a shallow dish; stir well. Spread mustard evenly over both sides of each steak. Dredge each steak in spice mixture.
Place steaks in preheated skillet; cook 3 minutes on each side or until desired degree of doneness (outside of steaks should be charred but not burned).
Place steaks on each of 4 plates; spoon Orange-Balsamic Sauce evenly over each steak, and sprinkle with parsley.
NOTE: You can substitute four 4-ounce fresh tuna steaks for the beef tenderloin. Cook 2 to 3 minutes on each side or until desired degree of doneness.