Place garlic on a cutting board; sprinkle with salt.
Using the flat side of a knife, mash garlic.
Continue to mash until it reaches a paste consistency.
Transfer to a small bowl.
Stir in the oil, rosemary and pepper; brush over pork.
Let stand for 20 minutes.
Grill pork, covered, on a lightly oiled rack over medium heat or broil 4 in. from the heat until a thermometer reads 145°, 9-11 minutes on each side.
Let stand for 5 minutes before slicing.