Prime grade beef is the absolute highest quality beef available, graded by the USDA. This is a very rare, and thus very expensive, only averaging about 3% of all carcasses. The beef has very minor, but a good amount of fat running through the meat, resulting in an amazingly juicy and tender cooked piece of meat.
Beef brisket full flat boneless comes from the brisket (breast) section and is cut from the rear portion of lean meat and fat closest to the plate layers. The breast and rib bones are removed. Often cured in salt brine to make corned beef brisket, it is usually prepared by braising or by cooking in liquid.