For rub, combine 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 degree F oven. For medium rare, roast for 30 to 35 minutes or until meat thermometer registers 140 degrees F. Cover with foil and let stand 15 minutes. The temperature of the meat after standing should be 145 degrees F. (For medium, roast for 40 to 45 minutes or until meat thermometer registers 155 degrees F. Cover and let stand 15 minutes. The temperature of the meat after standing should be 160 degrees F.)