- 1 2″-thick porterhouse steak (about 3 pounds)
- 1 tablespoon kosher salt
- 1 tablespoon light brown sugar
- 1/2 teaspoon cayenne pepper
- 4 cups rice bran oil or vegetable oil
- 4 tablespoons unsalted butter
- 1 teaspoon spice mix of choice (we like vadouvan; any masala will also work well)
- Score the steak 1/4″ deep over all surfaces (sides, too) in a crosshatch pattern, spacing cuts 1″ apart.
- Mix salt, sugar, and cayenne in a small bowl and rub mixture all over the meat, really massaging it into the score marks and crevices. Upend the steak—balancing on the flat side of the bone—on a wire rack set inside a rimmed baking sheet (this combo of rack and sheet allows air to circulate) and chill, uncovered, in the refrigerator overnight.
- Transfer the steak, still upright on the rack, to the freezer and freeze solid, at least 6 hours and up to 24.
- Preheat your oven to 200°. Pour oil into a skillet (it should be about 3/4″ deep) and heat over medium-high until a deep-fry thermometer registers 350°. Transfer frozen steak to skillet and cook, turning once, until all sides, including the fat cap, are deeply browned and a crisp crust has formed, about 3 minutes per side. Oil should come halfway up side of steak—add more if needed.
- Return steak to rack and baking sheet, this time laying it flat. (Reserve skillet and oil off heat.) Roast in oven until steak is no longer frozen (the interior will still be cold but thawed enough to allow the insertion of a probe thermometer), 30–35 minutes. Meanwhile, make the spiced brown butter.
- Cook butter in a small saucepan over medium heat until it foams, then browns, 5–8 minutes. Remove from heat and stir in spice mix of your choice. Let butter cool, 20–25 minutes, then strain through a fine-mesh sieve into a small bowl.
- Remove the steak from the oven and spoon about a third of the spice-infused butter over, turning to coat both sides. Poke thermometer probe into the center of the strip side and roast steak, basting every 30 minutes or so with remaining butter, until thermometer registers 120°, another 1–1 1/2 hours. (Alternatively, use an instantread thermometer to check steak every 15 minutes after the first hour, and again every 5 minutes after 1 1/2 hours. Once thawed, the temperature of the steak will rise about 1 degree per minute, so use that as a guide.)
- Remove steak from oven. Reheat reserved oil in skillet back to 350° over medium-high. Give steak a second fry, turning once, until a deeply browned crust forms on all sides, about 2 minutes per side. Transfer back to rack and let rest 10 minutes; this redistributes the juices inside the steak (resting: another pro move). Why sear again? It not only recrisps the first crust that softened during roasting, it also locks in juices and further develops flavor.