Season steak on both sides with the salt and place on a rack set inside a sheet pan. Refrigerate for a minimum of 8 hours, or up to 16 hours.
Heat oven to 200ºF.
Insert a probe thermometer horizontally through the side of the steak and roast the steak until it reaches an internal temperature of 120ºF, about 30 minutes. Remove steak from the oven and rest, uncovered, for 10 minutes.
Meanwhile, place a 12-inch cast-iron skillet over high heat until it reaches at least 600ºF, about 10 minutes. You'll know you're close when 1/2 teaspoon water dropped in the middle of the pan is completely evaporated in 5 seconds.
Brush a very light coat of peanut oil onto both sides of the steak. Sear steak on each side for 1 minute.
Rest the steak on a wire rack for 5 minutes, and then slice diagonally, against the grain, to serve.