Flank is thin, so use very high heat to get a good char in the short time it will take the steak to cook. Also, flank is so thin that a thermometer might not give you a good reading, so the press test will help. Take your index and poke a flank steak to measure its texture. If it feels and bounces back like poking your cheek, that’s rare. Your firm chin is medium-rare. The firm, unyielding tip of your nose is well-done. With thicker steaks, use a thermometer to test for doneness. Flank steak also goes by the name carne asada. You can also substitute skirt steak for this recipe. This cut is best cooked rare to medium-rare. Any further cooking will be really tough to eat.