Line a sheet pan with foil and place a wire rack on top, set aside.
Adjust oven rack to the center position and preheat oven to 275ºF (135ºC).
Place a large 12-inch cast iron skillet in the oven to warm, on a rack below the center rack.
Dry the steaks with a paper towel to remove excess surface moisture and transfer to the wire rack.
Generously season the meat with salt and ground black pepper on both sides.
Place steaks in the oven and cook about 15 to 25 minutes, depending on the thickness. See notes for target temperatures of the steak.
Remove the steaks from the oven and set aside.
Remove the cast iron pan from the oven and transfer to the stovetop.
Heat pan over high heat and add oil.
Once the oil is very hot and just beginning to smoke, carefully add the steaks to the pan.
Sear the first side until a deep brown crust is formed, about 2 minutes.
Carefully flip the steaks over and sear about 1 ½ to 2 minutes.
Use tongs to turn the steaks on their sides to cook and render remaining fat, about 2 minutes total.
OPTIONAL: Add one tablespoon of the butter to the pan, melt and use a spoon to briefly baste the tops of the steaks.
Transfer steaks to a clean plate and allow to rest at room temperature for 10 minutes.
Serve steaks warm.
When steaks are in the oven, check the temperature of the steaks using an instant-read thermometer at 15 minutes, then every 5 minutes until target doneness is reached, 90 to 95ºF (32 to 35ºC) for medium-rare, or 100 to 105ºF (38 to 41ºC) for medium.
When steaks are searing, aim for an internal temperature of 120 to 125ºF (49 to 52ºC) for medium-rare, or 130 (50ºC) for medium.
MAKE IT DAIRY FREE: Omit the butter.
MAKE IT PALEO: Use ghee instead of vegetable oil and butter.