Roasted Pork Loin with Orange Herb Sauce

In a large bowl, combine 2 tablespoons of the oil with the garlic. Add the pork, turn to coat and let stand for 1 hour. Set a rack in the upper third of the oven and preheat the oven to 400 degrees F. In a medium ovenproof skillet, heat the remaining oil. Season the pork with salt and pepper and add to the skillet, fat side down. Cook over moderately high heat until richly browned, 4 minutes. Brown the pork on the remaining sides, then turn it fat side up. Add the orange juice, stock, wine, peppercorns and herb sprigs and bring to a boil.
Transfer the skillet to the upper shelf of the oven and roast the pork for about 35 minutes, until an instant-read thermometer inserted in the center registers 145 degrees F. Transfer the pork to a carving board.
Strain the cooking liquid into a saucepan and boil until reduced to 1/2 cup, 15 minutes. Season with salt and pepper; stir in the chopped parsley. Carve the pork and serve with the sauce.