As far as festive meats go, it's hard to beat prime rib. We've written plenty on the subject, including a deep dive on how to cook it as well as how to smoke prime rib. But today we're talking about a method for cooking the very tenderest prime rib ever, with minimum oven time and no worries about overcooking. That's right: we're cooking our rib roast sous vide. We'll talk tools, temps, times, and techniques, so read on for the very best prime rib we've ever made.
Why sous vide a prime rib?
Cooking your prime rib sous vide may seem unorthodox, but it pays out in big dividends. First, there's the ease of cooking. You put it in a bag and drop it in the water bath. Then you come back a long time later, and it's practically done. Easy. Ok, it's not that much easier than a standard prime rib roast, but it moves the effort further away from dinner time, which gives you more time and oven space for other things closer to dinner.
But the biggest edge sous vide prime rib has over roasted prime rib is the tenderness caused by enzymatic action. Two groups of meat enzymes—calpains and cathepsins—work to break down different parts of the meat that make it chewy. The calpains deactivate when they reach 105°F (40°C), while the cathepsins don't shut off 'til they reach 122°F (50°C). So the longer your meat takes to move through those temperatures, the more tender it will be. In the case of our roast, we were in the enzymatic action zone for 5 hours, which made this the tenderest prime rib we've ever had.
What about the seared flavor?
Unseared meat doesn't taste amazing. And it sure doesn't look amazing. But on a cut as big as prime rib, there's precious little sear flavor that comes with each slice. Yes, we want what we can get, but we don't need much to approximate a thorough roasting. Once the roast has left the water bath, we can dry it off a little, then toss it under the broiler to pretty it up and activate those smells and tastes. About six minutes under the broiler should do it.
Boneless or bone-in prime rib for sous vide?
Buy what you want, but you'll need to cut the bones off before you vacuum-seal it. It's just too risky that they'll puncture the bag and drown the meat.
How long does it take to cook a prime rib sous vide?
Our 5-rib roast took about 18 hours to cook. Yes, 18 hours. That means that dinner at 5 means putting it on to cook at 11p.m. the previous day! But all of that time is hands-off, except for 6 minutes under the broiler.
Your time may vary, of course. A larger-diameter roast will take more time (though a longer roast won't, because of how the geometry works out). A roast that starts colder will take longer; a warmer roast will take less time.
Also, you can vary the cook time on your rib by fiddling with the water temperatures. You could, conceivably, turn the heat up a little bit (not more than 5°F) once you pass an internal temperature of 122°F (50°C). That will speed things up, but won't significantly impact the final doneness. There is room for experimentation here, though you may want to experiment on a cheaper cut (such as eye of round) before you throw $150 of prime rib in the bag.
Isn't that long a cook a food safety concern?
In short, no. Our cooking water will be at 136°F (58°C), and the outside of the meat will be in contact with that temperature for many hours. It takes only about 80 minutes in fat-rich tissue to kill salmonella at that temperature, and we'll be at that temp much longer. What about the interior of the roast? Not really a problem. Almost all bacterial contamination happens during butchering, and is spread on the surfaces of meats. The bacteria do not delve deep into the tissues and lie in wait [footnote]Balrog-style[/footnote] to infect us. And we'll broil most of the surface anyhow. This is as safe as medium-rare oven roast.
Can you cook it longer?
Yes, you can leave your meat in the bag longer, but it is a game of diminishing returns. Do it for the convenience, not for the added tenderness: put it on at 9p.m. instead of 11 so you can have a better night's sleep, not because you'll get 2 hours more tenderness out of it.
Do I even need a thermometer for this?
Yes! Sure you could toss the vac-sealed roast in the water and let it ride for the better part of a calendar day, but then you won't notice that (perhaps) your water level dropped and your circulator shut down and the water was venting heat. If that were to happen, your app-connected Signals could alert you to the fact so you could remedy the situation as fast as possible. (This is the sous-vide equivalent of running out of pellets in a pellet smoker). It happened to me!
You can see I had to run back into the office, top off the water level with some more hot water, and get things cranking again. Don't risk it! Use a thermometer!
An expensive, celebratory cut of meat like this is worth doing right and this is the right-est way we've found to do it. It comes out fall-apart tender, juicy beyond measure, and gorgeously pink from edge to edge. If you have a circulator, give it a try. Hook your Signals up, crank the water bath up, and go. You may never go back to roasting ever again. Happy cooking!
