He reveals the secret in the video. A carbon steel pan. That's it. The pan takes an incredible amount of heat. Up to 700F. The skin sizzles and in seconds is perfectly seared. A quick flip to char the flesh and then into a 350F oven to cook the filet on the inside.
A cast iron pan also works well at high heat, but from my experience the carbon steel pan does a better job. Both pans are relatively inexpensive. A carbon steel pan will cost half the price of a comparably sized, quality stainless steel pan. When you shop for a carbon steel pan, buy one that is made with a thicker gauge steel. I have been using de Buyer pans. Chef Boudreaux recommends Matfer Bourgeat. The advantage of the thicker gauge pans is they retain heat longer than the pans made with a thinner steel.
Cast iron pans are easy to find. Carbon steel pans, not as much. In the Los Angeles area, the only source for the pans is Surfas Culinary District. In New York, I have seen them upstairs at Zabar's.
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