Heat oven to 325°. Combine rub ingredients; reserve 2 tablespoons for potatoes. Press remaining rub onto roast. Place roast on a rack in a shallow roasting pan. Roast for 1-1/2 to 1-3/4 hours for medium rare doneness. Meanwhile mix reserved rub with 2 teaspoons water and toss with potatoes. Roast in a greased baking pan, covered, for 1 hour. Stir potatoes and continue to roast, uncovered, for 10 to 15 minutes or until tender. Remove roast when meat thermometer registers 135° for medium rare. Let stand 15 minutes. (Temperature will rise to 145°.) Carve and serve with potatoes.