Preheat oven to 450 degrees. Combine salt and pepper in a smaller size bowl. With a sharp knife cut a line down into the rib roast staying 1/2" from the front to create a big pocket in order to stuff with rosemary and garlic. Sprinkle about half of the salt and pepper into the pockets and add rosemary and garlic. Make sure that the Rosemary sprig is poking out f the pocket.
Tie the roast (between the ribs .with kitchen twine) and sprinkle the remaining salt mixture on the outside of the roast. Place in a large roasting pan with the ribs pointing up.
Cook for 15 minutes on 450 degrees F. then reduce heat to 350 degrees F. until it reaches the desired temperature.
Rare = 130 degrees F. Medium = 140 degrees F. Depending on your oven this can take between 65-85 minutes for rare and 90-120 minutes for medium.
Remove from oven and tent with foil, let rest for 30 minutes. Remove the rosemary and cut the string. Slice and serve.