One thing about being an engineer, is that unless I’m jetlagged or drunk (very rare), there’s always a part of my brain questioning how something works. And when we decided to make prime rib for our circle of friend’s New Year Eve party, I was pretty baffled at some of the recipes that I’ve dug up during my course of research. Inevitably, there would be a blurb along the lines of:

“the roast will continue to cook from its own heat during this time. This will give you about 10 more degrees F.”

And the little voice in my head says,

“Well, where is that heat coming from?”

Since a 4-rib prime rib roast is a serious chunk of beef, commanding a equally serious price, an experiment and a test run was in order. I procured a smaller cut of chuck roast to cook in the smoker before committing the resource and my reputation as a BBQ guy to supply the finished roast. And, following the instructions online to the letter, I targeted 140 deg F for medium rare, and pulled the chuck roast sample at 130 deg F and let it rest for 20 minutes.

The beef might as well be mooing as we cut into it. So much for “the roast will continue cooking…”

IMHO – the “10 deg gain” is one of those tidbits that’s blindly parroted around. In a conventional oven cooking of a roast, the oven is set to ungodly high heat (500 deg F on some recipes) to sear a crust onto the roast. The heat is then dialed down over the course of time. Due to the thermal mass of the roast and the fact that the thermometer is being poked into the center of the meat, there exists a temperature gradient between the outside surface and the inner core. Of course, during the “resting” stage this thermal energy redistributes itself throughout the roast, resulting in a temperature rise. Naturally, this would be dependent on variables such as the temperature used to cook the meat, and the mass and diameter of the meat itself. Bigger distance, higher temperature, more temperature rise. Another way to think of it is that the thermometer reading *lags* behind the actual temperature of the roast. This is what my engineering Dad calls, “a rubber screwdriver”.

My theory is to “reverse sear” the meat. This is what I did:

Here’s my roast from QFC – USDA Choice prime rib. The bones had already been sliced off and the excess fat trimmed off when I acquired it. All I have to do is to season the roast. Unpacking the meat I rinsed any blood or meat juices that had gathered on the meat and patted everything dry with kitchen towels. I then made a paste out of crushed garlic, cracked black pepper, sea salt, thyme and rosemary. Terence’s rule of fat applies here: I used half a stick of butter along with some olive oil for the fat to make my spice paste. (In general, I found that you really can’t go wrong with fat rendered from the same animal in a roast – so a bit of bacon fat for pork dishes, or a bit of butter for a beef dish, goes a long way).

The spice paste is massaged into the meat, and into the seam between the rib bones and the prime rib portion, then the roast is tied back together using kitchen twine. This then goes uncovered into my refrigerator on a rack, on a baking pan with some kitchen towels underneath, to dry the exterior surfaces of the meat off a bit. (If I left it there long enough, it would technically be dry-aging, but I am concerned about my ability to pull of dry aging properly, and didn’t really want to experiment *that* much with my friends. Next time…)

The next day, I set up the smoker. Here, I’m loading mesquite charcoal into the bottom for fuel. I’ve learned that larger chunks tends to burn more slow and uniform and is much less prone to thermal runaway. On another cooking run I had loaded the smoker up once with small briquette-sized chunks and a thermal-runaway killed two strips of my famous BBQ pork. *sob*.

Onto the charcoal goes about 4-5 mesquite chunks and a handful of mesquite chips. I then dump a lit half-chimney full of briquette sized charcoal chunks to get everything going.

Here’s a recycled picture from me smoking the thanksgiving turkey. For this smoke, the temperature never exceeded 210 deg F. Which meant that the roast temperature crept up *slowly*

After the roast hits 148 degrees – we had ladies at the dinner table that don’t care for medium rare beef – I removed the roast from the smoker and wrapped it up in foil to drive it to my buddy’s house. There, we seared the crust on as part of the serving routine. (We seared it in a 500 deg F oven, but in hindsight, I would have used a hot cast iron skillet next time).

There you have it. It’s a perfect medium all the way out to the crust. Low and slow cooking is the way to go.

The only negative was that the mesquite smoke was too strong in some spots. Fortunately, the smoke didn’t penetrate too deeply into the meat.

Next time, we’ll use old oak wine barrel slats for the smoke source to get some of that wine-infused smoke, and use a cast iron skillet to sear the crust.