Step 1

Season steak generously with kosher salt and pepper and let sit at room temperature 1 hour.

Step 2

Heat a dry large skillet, preferably cast iron, over medium-high, then add oil. As soon as oil is smoking, cook steak, turning every 2 minutes or so, until a deep brown crust forms and the internal temperature is a few degrees below your favored doneness (120°–125° for medium-rare), 8–10 minutes.

Step 3

Add butter, rosemary, and garlic to skillet, tilt pan toward you so that butter pools on one side, and use a large spoon to continually baste steak with butter. Continue until butter is no longer bubbling and it smells nutty and is beginning to brown, about 1 minute. Transfer meat to a cutting board and let rest 10 minutes. (For medium-rare, your steak should reach an internal temperature of 125°–130°.)

Step 4

Cut meat from bone and slice against the grain 1" thick. Spoon some infused brown butter over steak and sprinkle with sea salt.Read More: The 29 New Essential Recipes from the Bon Appétit Test Kitchen