1. Combine all ingredients except beef in a large glass or plastic container and mix well.
2. Trim beef of fat and add to marinade, cover and refrigerate for 24 hours, turning occasionally.
3. Remove tenderloin from marinade and place on top rack of a covered gas grill.
4. Close cover. Keeping heat low, turn meat occasionally and baste with remaining marinade.
5. Cook about 1 hour or until desired doneness is reached.
6. Let the cooked beef rest for about 10 minutes and cut into filets.
7. Discard marinade. Serves 12.
8. Serve with mushrooms sauteed in butter, or horseradish sauce.