Let the steak come to room temperature for 30 minutes. Preheat the grill to high heat.
Sprinkle the steak generously with salt and pepper on both sides and grill over high heat, about 6 minutes per side. You're looking for a nice crust on each side, but to be true to the Fiorentina method, it should be rare on the inside. If you prefer not to eat your meat rare, cook it a little longer on each side, about 8 minutes per side for medium and longer for well done.
Then let it rest for about 10 minutes before you carve into it.
Cut the steak off of the bone, carving the strip off on one side and the filet off on the other. Then slice the meat against the grain and serve it on a cutting board or platter with the bone (true Fiorentina style).
NotesCook's Note: The wife likes her steak a bit more done than I do. That's ok- there will always be a more well-done portion of the steak near the outside, and the parts closer to the bone will be more rare!