Rich and flavorful (and pricey), prime rib is typically reserved for special-occasion meals, like our holiday menu. What you may not realize is that the term “prime rib” has two definitions. It refers to both a particular cut of beef and to a USDA grade of beef. To help you talk the talk at the butcher counter, here’s an in-depth explanation of “prime.”
Prime rib: the cut
A prime rib roast, or standing rib roast, is cut from the back of the upper rib section of the steer, and it usually comprises a total of seven ribs. To make the Slow-Roasted Prime Rib, you’ll need a three-bone rib roast, which can be cut either from the chuck end or the loin end of the rib section.
The chuck end (aka the large end or second cut) is bigger in overall size, but it has a smaller rib eye, with several thick layers of fat interspersed between portions of lean meat.
Author Suzanne Goin prefers a three-bone rib roast cut from the loin end—called the small end or first cut. It’s smaller in overall size, but it has a larger rib eye, meaning more meat and less fat.
Prime: the grade
Prime is the best USDA grade of beef available, having the most marbling (flecks of fat interspersed in the meat) and therefore the best flavor and tenderness. Because of its expense, most Prime beef ends up in restaurants. The grade below Prime is Choice, the grade most supermarkets carry. When you ask for a prime rib at a supermarket, chances are the counterperson will assume you’re referring only to the cut, not the grade, and you will receive a Choice grade prime rib. The quality of Choice grade beef is still quite good, and since a rib roast is a rather fatty cut to begin with, a Choice grade prime rib will make a fine roast. That said, if you want to splurge on the best, you’ll need to order a prime (grade) prime rib, and you may have to seek out a specialty butcher shop or high-end supermarket to find one.