It only takes around six minutes to cook a flat iron steak to medium rare, and it should rest for about eight minutes. You shouldn't rely on the hand trick to check the meat's doneness; instead ...

Flat iron’s name comes from its triangular shape resembling old clothes irons, and the New York landmark, the Flat Iron Building. Another name for flat iron is top-blade steak.

Place the flat iron steak on the grill over medium-high heat and grill about 8 minutes on one side. Turn and continue grilling another 6-8 minutes or until medium-rare (or desired degree of doneness).