After searing and resting, the meat will reach around 140°F, leaving you with a roast that’s perfectly rosy pink from edge to center. Similarly, I cook pork to 140°F and chicken or turkey breasts to 145°F. The USDA recommends an unconscionable 165°F for poultry, but I prefer to take my chances for the sake of moist chicken.
The Perfect Sear
Tender and juicy interiors pair best with a crispy, charred exterior. And the technique to getting the perfect sear from an outdoor grill comes down to the three ways through which heat is transferred: convection, conduction, and radiation. With convection, energy is transferred to a fluid medium like air, oil, or water. That hot fluid then flows over and around the food, transferring some of its energy to it. As we know, air is relatively poor at transferring heat. Water is better, but limited by its 212°F temperature limit (above that, it converts to steam). Oil is better than air and worse than water, but can be heated much higher—usually up to around 400°F or so before it starts smoking or catching on fire. This temperature range is hot enough to catalyze the Maillard reaction, the complex cascade of chemical reactions that turn your food brown and add dimension to its flavor.
But you can’t very well fill your grill with hot oil. And that’s where radiation comes in. Radiation is the direct transfer of energy through space via electromagnetic waves. This method doesn’t require any sort of direct contact with a cooking medium—not water, oil, or air. Because of this, it is an extremely efficient means of transferring energy. Hot coals will emit a ton of electromagnetic radiation in both the visible spectrum and the infrared spectrum (fancy words that describe the length of the waves emitted). Put your food close to these hot coals, and that energy gets absorbed into its surface, causing it to heat up and brown. We cook via radiation every time we sear foods on the grill.
The final method of heat transfer is conduction, or the transfer of heat from one object to another by direct contact. It’s the primary means of energy transfer when you pan–sear a chicken paillard, or sauté vegetables. On a grill, it’s what results in those pretty grill marks. Light up your coals, cover your grill, and allow it to preheat for about ten minutes. By this point, the metal grill bars will have absorbed enough energy that they’ll very rapidly char the surface of the food they come in contact with. Grill marks aren’t just about good looks: They deliver valuable flavor and textural contrast, lending more complexity to your food.
Allowing your grill bars to preheat provides another benefit: It helps prevent sticking. Have you ever placed a salmon fillet over hot coals, only to have it shred apart as you try to flip it? This is because when you place cold protein on a grill, the metal in the grill grates actually forms a chemical bond with the proteins in the meat—and it’s a bond that’s very tough to break. With more robust meats like beef, lamb, or chicken, this isn’t a problem, as the meat proteins stick to each other better than they can stick to the grate. But for delicate meats like fish or hamburgers, this can be a big problem. When you get your grates hot enough, the proteins near the surface of the meat will actually cook so quickly that the grates won’t have a chance to bond with your meat.
From crafting the perfect bed of coals to flipping a stick–free salmon steak, you need much more than luck and a toque to master your grill. So the next time you fire up the flames or ignite a chimney of charcoal, stop and think about the science that’s being cooked up under the cover.
Kenji Lopez–Alt is the managing editor of SeriousEats.com.
For more on grilling, see our sister site, Epicurious.com.—Ed.