Place a cast-iron skillet directly on the coals or hot rocks and allow to heat until it begins to smoke. While the pan is heating, season the steak liberally with salt and pepper. Add oil, garlic and thyme to the pan. The oil will shimmer and bubble; when it does, quickly add the steak. Sear until the steak browns halfway up the side, about 4–6 minutes, then flip.

Add butter and cook on the other side until your steak hits 5° less than your desired finished internal temperature (or 4–6 minutes for medium-rare). Baste with butter as it finishes. Remove steak to a plate and let rest.

Slice steak across the grain to serve and top with pan juices.