Preheat oven to 500°.
Season the steak on both sides with sea salt and fresh ground pepper.
Heat a cast iron skillet large enough to fit the steak snugly.
Add the butter and oil to skillet and when butter is melted add the seasoned steak and sear on each side, about 1 minute each.
Slide the pan into the oven for approximately 5 minutes, be sure to use a probe type thermometer. Cook the steak to 130° for medium rare and let rest for about 4 minutes before serving. Slice on the bias, against the grain and serve.