Secure tenderloin at 2" intervals with heavy string. Place tenderloin in a large zip-top freezer bag.
Combine port and next 4 ingredients; stir well. Pour marinade over tenderloin; seal. Marinate in refrigerator 2 hours, turning bag occasionally.
Remove tenderloin from marinade, reserving marinade. Pour liquid through a wire-mesh strainer into a bowl; reserve garlic and discard solids. Set 1 cup marinade aside.
Place tenderloin on a lightly greased broiler pan. Insert a meat thermometer into thickest portion of tenderloin. Place tenderloin in a preheated 425° oven. Immediately reduce heat to 350°; bake, uncovered, for 1 hour or until thermometer registers 145° (medium rare) to 160° (medium) or to desired degree of doneness. Let stand 10 minutes before slicing. Remove string.
Combine reserved garlic and 1 cup reserved marinade in a small saucepan; bring to a boil. Reduce heat, and simmer 8 minutes or until reduced by half. Remove and discard garlic. Stir in cranberry sauce, salt, and pepper. Bring to a boil; cover and simmer 1 minute. Garnish, if desired. Serve with Cranberry-Port Reduction and Gorgonzola Butter.
Note: To roast the vegetables for garnish, drizzle lightly with olive oil, and sprinkle with salt and pepper. Roast at 450° for 15 minutes, stirring once.