Salt steak on both sides and leave at room temperature for 45 minutes. Preheat the oven to 200 degrees. Lightly spray a rimmed baking sheet with cooking spray
Sprinkle black pepper on the steaks. Place steaks on the baking sheet and transfer to the oven, cooking for 20 minutes. Check the temperature and continue cooking, if needed, to your desired temperature range
Heat a skillet over medium-high heat with a drizzle of oil. Sear flat iron steak for 1-3 minutes on each side. Move to a clean plate to rest for five minutes before serving