1. For brine, microwave 2 cups water in a microwave proof bowl on High 3 minutes, until steaming. Stir in apple, the kosher salt, sugar, garlic, peppercorns and sage until sugar has almost dissolved. Add 2 cups cold water. Cool to room temperature.
2. Pour brine into a large, heavy-duty, resealable plastic storage bag. Add pork. Push out excess air from bag and seal. Marinate pork in the refrigerator 24 hours, turning the bag several times.
3. Spread the two apples in an 11x7-inch baking dish; set aside. Combine garlic, sage, oil, vinegar, pepper and salt in a cup; set aside.
4. Heat oven to 350 degrees F. Drain pork in colander; discard brine and solids. Rinse pork under cold running water. Pat dry. Rub pork with garlic mixture and place on top of apples in baking dish.
5. Bake pork and apples until an instant-read meat thermometer inserted in center of pork registers 160 degrees F, about 60 to 70 minutes. Transfer pork to a serving platter and cover loosely with foil. Remove apples from baking dish, coarsely chop and transfer to a bowl; skim fat from drippings in pan. Stir drippings into apples. Serve pork with apples. Makes 6 servings.