Mince garlic and whisk together with remaining ingredients. Rub mixture all over steak and marinate for 30 minutes, or up to 24 hours.
Preheat broiler to high, with oven shelf positioned 5-6 inches below. Preheat a 10" or 12" cast iron skillet in oven for 5-7 minutes. If all the steak won't fit in one pan, do it in batches.
Carefully remove cast iron skillet from oven, and drop in steak. Return to oven. Cook for 2 minutes per side, until the internal temperature reaches 125 degrees F for medium rare, or 130 degrees F for medium. Be sure to let the steak rest for 10 minutes after pulling from the oven, then slice.