Put the fatback, garlic, and rosemary into a food processor and blend until it is the consistency of toothpaste.
Tie the rib in the correct way so that it is tight and will cook evenly.
Rub the fat mixture all over the meat and season with salt and pepper. Place it on a very hot grill. Cook the steak on 1 side for about 8 minutes. You can move it around a little bit to find the right heat. Turn it over and cook it a little bit less on the other side, about 6 minutes.
When it is finished, take it off the grill and let it rest for 5 to 7 minutes. This allows the blood to circulate and allows the juices to distribute evenly.