The term “prime rib” is often incorrectly used for what is really a rib roast. The word prime is derived from the highest grading beef can obtain from the USDA, due to its marbling and fat content. Most true “prime ribs” are used by high end steak houses and swanky hotels, leaving only the choice USDA grades to be found at most supermarkets.
However, there is no law against a restaurant calling a roasted “choice grade” rib of beef “prime rib” because who’s to say that they didn’t roast it in a “prime” fashion.
So why call this post “How To Cook Prime Rib” even though its really a rib roast? Because that’s what people know it as and will keep calling it no matter how incorrect. But at least now you know the real truth. So without further delay…
How To Cook Prime Rib
- When cooking prime rib, I like to always heavily salt the rib roast the day before and leave it in the fridge overnight. If you salt the rib roast right before cooking, it will draw moisture to the surface through osmosis and retard the browning process.
- A lot of people like to start their “prime rib” in a 300-350 degree oven in order to keep it from shrinking. Me personally, I like to roast it first at 500 degrees for about 15 minutes to give the meat a little jump start on the browning process
- Start by heavily seasoning your rib roast with lots of kosher salt and pepper and letting it sit in your fridge overnight if at all possible.
- Place the rib roast fat side up in a roasting rack, and place the roasting rack in a roasting pan. If the fat cap is thicker than 1/2″, trim it down accordingly.
- Insert a probe thermometer into the center of the rib roast, (this step can be omitted if you are using an instant read thermometer).
- Place the rib roast (aka prime rib) into a 500 degree oven for about 15 minutes to help the browning process begin.
- After 15 minutes, lower the oven to 300 degrees and allow to cook until it reaches the desired internal temperature, (120 degrees F for rare, 130 Degrees F for medium) allowing for about 10 degrees of carryover cooking. This means that for medium, you should really pull the rib roast out of the oven when your thermometer reads 120-125 degrees Fahrenheit. Note: end pieces will be more done than the center.
- After the desired internal temperature is reached, remove from the roasting rack and allow to “rest” in a warm place for about 15-30 minutes. This will cause the juices to evenly distribute back into the meat, keeping your prime rib moist when slicing.
While your prime rib is resting, it is the perfect time to make your pan jus from the drippings.
- Put the roasting pan on the stove top on medium-high heat. If there is an excessive amount of fat in the drippings, you can pour some of it off, being careful not to lose any of the meat juices.
- Throw in some mirepoix (diced onions, celery and carrots at 2:1:1 ratio respectively) and brown in the fat drippings.
- Once the mirepoix is nice and browned, add in some roasted veal stock at the rate of 1/2 gallon per 10 lb prime rib. Allow to simmer and reduce by at least 1/2, making sure to scrape all of the little brown meat drippings off the bottom of the pan.
- Strain through a chinois into a sauce pot, and allow to sit off the flame so that the fat has a chance to rise to the top. Skim off the fat, and finish your jus by seasoning with salt and pepper to taste.
- Serve your prime rib with some sort of potato (baked, mashed, fried, etc), a good seasonal veg, some horseradish sour cream, and of course your natural pan jus.