Combine port through bay leaf in a shallow dish or a large heavy-duty zip-top plastic bag. Place tenderloin in marinade. Cover or seal, turning to coat. Chill 8 hours, turning occasionally.
Remove beef from marinade, reserving marinade. Press pepper into beef. Place beef on a rack coated with vegetable cooking spray in a broiler pan.
Bring reserved marinade to a rolling boil in a small saucepan; reduce heat and simmer 3 minutes. Discard bay leaf.
Bake at 425°, basting 3 or 4 times with reserved marinade, for 45 to 55 minutes or until a meat thermometer inserted into the thickest portion registers 145° for medium-rare. Let stand 10 minutes.