For rub, combine the chipotle peppers, oregano, oil, cumin, salt, and garlic. Spread over surface of meat, rubbing in with glove-covered hands. Cover and chill for 6 to 24 hours.
Place meat on a rack in a shallow roasting pan. Insert an oven-going meat thermometer into center of roast. Roast in a 425°F oven. For medium rare, roast for 30 to 35 minutes or until meat thermometer registers 140°F Cover with foil and let stand 15 minutes. The temperature of the meat after standing should be 145°F (For medium, roast for 40 to 45 minutes or until meat thermometer registers 155°F Cover and let stand 15 minutes. The temperature of the meat after standing should be 160°F.).