In a large skillet heat 2 teaspoons of the oil over medium heat. Add onion; cook and stir until tender. Add sweet potatoes, apple, 1/4 teaspoon salt, and the cinnamon. Cook for 2 minutes, turning occasionally. Add 2/3 cup of the apple juice. Bring to boiling; reduce heat. Simmer, covered, for 10 to 12 minutes or until sweet potatoes are tender. Using a slotted spoon, transfer sweet potato mixture to a large bowl; set aside. Add the remaining 1/3 cup apple juice, the mustard, and brown sugar to skillet; cook and stir for 1 minute. Transfer apple juice-mustard mixture to a small freezer container. Seal, label, and freeze for up to 1 month. Fold a 36x18-inch piece of heavy-duty foil in half to make an 18-inch square. Spoon sweet potato mixture into the center of the foil square. Bring up opposite edges of foil and seal with a double fold. Fold the remaining edges together to completely enclose the sweet potato mixture. Seal, label, and freeze for up to 1 month.
Thaw sweet potato packet and sauce overnight in the refrigerator. Preheat oven to 400 degrees F. Place sweet potato packet on a baking sheet. Open packet to expose the top of the sweet potatoes. Bake about 25 minutes or until heated through.
Meanwhile, prepare the pork. Cut pork tenderloin crosswise into eight slices. Place each pork slice between two pieces of plastic wrap. Using the flat side of a meat mallet, pound pork lightly until about 1/2 inch thick. Place 1/4 cup of the flour in a shallow dish; set aside. Place eggs in another shallow dish. In a third shallow dish combine the remaining 1/4 cup flour, the ground pecans, 1/4 teaspoon salt, and the pepper. Dip pork slices, one at a time, into flour, turning to coat and shaking off excess. Dip pork slices in eggs and turn to coat, then dip in pecan mixture, turning to coat.
In a 12-inch skillet heat 2 teaspoons of the remaining oil over medium-high heat. Add pork slices; cook for 3 minutes. Turn pork; add the remaining 2 teaspoons oil to the skillet. Cook about 3 minutes more or just until slightly pink in center. If pork browns too quickly, reduce heat to medium.
While the pork and potatoes are cooking, transfer sauce to a small microwave-safe bowl. Microwave on 100 percent power (high) for 1-1/2 to 2 minutes or until heated through. Just before serving, whisk in the chives.
Divide sweet potato mixture among four warmed dinner plates. Place two pieces of the pork beside sweet potatoes on each plate. Drizzle with the sauce and sprinkle with the toasted pecans. Serve immediately.