The 5 Biggest Mistakes to Avoid When Cooking Prime Rib

Cooking the Roast Cold

Cooking cold meat is one of the biggest cooking mistakes there is because chilled meat needs to spend more time exposed to the heat, causing the outer parts of it to overcook. With prime rib, this mistake is amplified many times because of how massive the roast is. This extra weight means it takes a while to come to room temperature.

The problems that occur if you fail to let your prime rib come to room temperature will vary depending on which cooking technique you use. With the closed-door method, the weight-to-cooking-time ratio won't work if the prime rib starts ice-cold, and you'll end up taking it out of the oven too early. With the traditional method, you'll simply end up with an overcooked roast.

Start on the right foot by letting your prime rib sit at room temperature for a full 3 hours before roasting it.

Worrying About Seasoning

Yes, it's important to season your prime rib, but worrying about whether to season it the night before or three hours before—or even right before it goes in the oven—is not a good use of your cooking bandwidth. The fact is that no amount of seasonings you apply to the surface (including soaking in a marinade) are going to penetrate beyond about 2 millimeters into that massive roast. (This is why people inject brine into roasts.)

In fact, the longer the salt sits on the surface of the meat, the more moisture will get sucked out of it, which is the complete opposite of what you want. So by all means, salt and pepper generously, but you only need enough on the surface to season every bite, including the non-edge sections.

Just don't lose sleep about it. The most logical time to season your prime rib is at some point during the 3 hours you have it sitting on your counter coming to room temperature.

Overcooking the Prime Rib

Prime rib comes from the rib primal cut, which is the second-most tender of all the cuts of beef (after the tenderloin). That's why prime rib is so expensive: it's a huge piece of extremely good beef. Therefore, it's important not to cook it beyond medium-rare. Going past that temperature means the roast will no longer be tender.

This is not to say that you shouldn't cook your beef any way you like, but if you prefer your beef roasted medium, medium-well or well-done, you may want to consider cuts other than prime rib—perhaps a sirloin or a rump roast, for instance. You'll save at least $50, and you won't be missing out on the tenderness.

Poking the Prime Rib Full of Holes

The different levels of doneness are measured by temperature and medium-rare is defined as a peak temperature of 135 F. (You'll wait for it to cool to 120 F before slicing it, but more on that below.) But that doesn't mean you should determine doneness by taking repeated measurements using an instant-read thermometer. It's a prime rib, not a pincushion!

Fortunately, there are better methods. The standard prime rib roasting technique employs a probe thermometer that you insert into the meat and leave in while it cooks. When it reaches your target temperature, it's done, and you take the roast out of the oven, having only poked one hole in it. Even better is the closed-door method, which doesn't require a thermometer at all.

Remember, prime rib should be tender and juicy. Poking it full of holes causes those juices to leak out. Don't do it!

Not Resting the Prime Rib

Letting your prime rib sit at room temperature for around 30 minutes before slicing it is called resting it, and resting your prime rib helps ensure it will be as juicy as possible. When you roast a piece of meat in a very hot oven, the juices from the outer regions flee toward the center of the roast. The heat causes the proteins in the meat to contract, which literally squeezes the juices out of the cells. Slicing into the meat right away will just cause all those juices to come spilling out onto your cutting board.

If you let the meat cool to 120 to 125 F, those juices are reabsorbed into their cells, and when you slice it, very little juice actually escapes, which means each bite will be as moist as possible. If you're using one of the traditional methods with a probe thermometer, simply leave the probe in after you take the meat out of the oven. When the temperature dips to at least 125 F, go ahead and slice. The beauty of the closed-door method is that it requires barely any resting at all. Same with the slow-roast method.