Remove the steak from the fridge, season with black pepper and allow to sit at room temperature for 30 to 45 minutes before cooking.

Bring teres major steak to room temperature. Trim any silver skin from the meat. Pat steak dry with paper towels to remove excess moisture.

Place teres major steak on a plate or a lined small sheet pan. Season liberally with salt and black pepper. Let the meat sit at room temperature for up to 1 hour. Alternatively, follow instructions from the note above.

Preheat the oven to 400ºF (If the steak is less than 12 ounces, you may not need to use the oven to finish cooking the meat).

Heat a cast iron skillet or an oven-safe heavy stainless steel skillet over medium-high heat. Add the oil and butter then swirl the skillet to coat the bottom of the pan. When hot and shimmering, add the steak to the skillet.

Sear the meat undisturbed for about 2-3 minutes. Using kitchen tongs, rotate the meat and immediately add the rosemary and garlic.

Sear all sides, basting with butter and rotating the meat as needed. When all sides are seared, check for doneness. If your steak is about 12 ounces, most likely you will need to finish the cooking in the oven.

Check the internal temperature with an instant-read thermometer inserted into the thickest part of the meat. If the internal temperature is lower than 110 (43°C), place the skillet in the oven and cook until the meat reaches your desired temperature. 110ºF (43ºC) for rare, 120°F (49°C) for medium-rare or 130°F (54°C) for medium.

Remove from the heat (or oven) and transfer to a cutting board or plate and loosely tent with aluminum foil. Let the steak rest for 5-10 minutes before serving or slicing. Serve.