Preheat grill or oven to 350 degrees F.
Prepare marinade by combining the bourbon, brown sugar, soy sauce, cilantro, lemon juice, Worcestershire sauce, water, and thyme in a bowl. Make sure the tenderloin has been cleaned and the tissues has been removed. Fold the tail end of the beef back underneath itself so that it is of uniform thickness and secure with butcher's string. Place meat in a dish and pour marinade over meat, cover, and refrigerate for 4 to 6 hours, or up to overnight, turning meat over several times.
When grill is ready, place meat on oiled surface and reserve the liquid from the marinade. Cook over high heat with lid closed, turning meat often and occasionally basting with the marinade. Cook for approximately 25 minutes for medium rare.
Serve with horseradish cream on the side.