how long to cook sirloin tip roast
1 Preheat oven to 325Â°, place roast in pan and place on upper oven rack. 2  Cook for 25 minutes per lb for medium or approximately 50 to 60 minutes. 3  Use a meat thermometer to check doneness-should read 140Â° for medium. 4  Remove from oven, cover with foil to keep warm and let rest for 15 minutes before carving.irections. 1  Remove roast from refrigerator one hour before serving to bring meat to room temperature for more even cooking. 2  Mix together rest of ingredients and rub over roast. 3  Let set for one half hour. 4  Preheat oven to 325Â°, place roast in pan and place on upper oven rack.