I talk about this from time to time and try to explain how and why a steak that is thrown onto an open grill cannot optimize the true cooking temperatures. The basics are seen here in the video, a rushing steamy cloud of smoke off the topside of the steaks. So why?

The steak is cooling and its moisture is evaporating just the same when you sit in a hot and dry sauna and start to sweat. As the body sweats it cools and stays cool as long as the water evaporates and forms on your skin’s surface.

Actually the top surface temperature of the steak stays more or less under 100°C until such time that the food’s water is expended. This is defined as the wet bulb temperature. It can never be hotter than the dry-bulb temperature (the oven temperature) and the wet-bulb can never hotter than the boiling point of water 100°C.

Think about it, the wet-bulb temperature at the surface of the food quickly rises from its starting point to the maximum wet-bulb temperature. Then it stalls and remains there until the surface dries and the temperature rises.

The bottom-line is the steak begins to lose moisture (it steams) during the constant-rate period as the core gradually begins to lose more moisture. The steaks temperature rises to equal the wet-bulb temperature and then rises above 100°C and dries out.

The optimization is when you have a very high temperature such as 800°C – the steak gets seared as the moisture of the surface is instantly depleted and it gets zapped black. This stage of drying is called the falling rate period. It happens once the surface of the food becomes desiccated. Evaporation has raced ahead of the diffusion and the juices from the center no longer reach the surface to keep it wet. It’s then a delicious crust forms. Beneath the crust, however, the food is still moist, and evaporation continues.

http://mesubim.com/2014/11/08/steak-zapped-800c/