Pat tenderloin dry. Stir together pepper, bouillon, salt, cornstarch, oregano, garlic powder, and paprika in a small bowl. Rub oil all over tenderloin, then sprinkle with spice mixture, rubbing it into meat. Put tenderloin on rack in roasting pan and roast 10 minutes, then reduce oven temperature to 425°F and cook until thermometer inserted diagonally into center of meat registers 130°F, 20 to 25 minutes for medium-rare. Let beef stand on rack in pan 10 minutes before serving.