The point of resting the meat is to retain maximum moisture. It is for the same reason you want to flip often when searing. When the meat rests it gets time to redistribute the juices, which means a lot less juice leaks when you first cut it on the plate. It stays in the steak, meaning you will get a juicier steak.
See the pictures below which illustrates the point of resting meat. They were all cooked identically, to the same temperature. They were then rested 0 minutes, 3 minutes, 6 minutes and 9 minutes respectively. Each steak was placed on a plate, and cut in half. As you can see the steak that wasn’t rested at all leaked a lot of meat juice.
When is the meat done resting?
The easiest way to tell is to check with a thermometer. Its inner temperature should come down below 160° F, but must not be lower than 140° F.
Your average beef like sirloin or tenderloin typically needs a 10 minute rest (assuming an average weight of 7 oz). The same goes for larger roasts, but they need a longer rest period. A general rule of thumb is 10 minutes per 7 oz. A pork butt that weighs 2.2 pounds would need a 50 minute rest. A trick with roasts is to wrap them in aluminum foil and an old bath towel, and let it rest. This way temperature doesn’t drop too much.
But, doesn’t this make the meat go bad when it is cooling off?
No, not at all. First off, it isn’t cooling. We wrapped it in a towel, right? Single steaks like a sirloin rest for max 15 minutes, so the temperature drops 1-2° F, if at all. The same goes for roasts, I’ve let a 3lb pork butt rest for 1.5 hours and the temperature dropped only 5° F.
Leave the thermometer in while resting, and see for yourself.
How to rest meat
When it comes to roasts (not steaks), you simply wrap the meat in a double layer (yes, single layer won’t cut it) of aluminum foil. Wrap it as snugly as you can, the less air inside, the better. Also make sure you seal it up good, you don’t want either steam or juices to leak out. That is why two layers are the way to go. On top of that, you wrap an old bath towel. Use a bath towel, as they are thicker than a kitchen towel. Make sure you let the roast “steam off” for a few minutes before wrapping though, to get rid of any residual heat that would cause a continuing rise of temperature.
This is known as a “faux cambro”. A cambro is a plastic cooling container for food and beverages. The name originally comes from the Campbell Brothers. A “faux cambro” is in other words a “fake cooling container”.
Resting steaks vs roasts
Here’s a chart that should help guide you.