Place the apple juice in a pot, bring to a boil, and reduce to 1/2 cup. Remove from the heat; mix in the mustard, sugar, vinegar and herbes de Provence. Preheat the oven to 350 degrees F. Set the pork in a roasting pan; season with salt and pepper. Roast 80 minutes, and then brush with 1/3 of the glaze. Roast 10 minutes more; brush with 1/3 more of the glaze. Roast 10 minutes more, and then brush with remaining glaze. Roast another 10 minutes, or until the centre of the thickest part of the roast reaches 160 degrees F. Transfer to a large plate; drizzle with pan juices. Tent with foil and let rest 10 minutes before slicing.