Combine the figs and 2 cups of the apple cider in a medium saucepan and heat to a boil. Cook, covered, over low heat until the figs have softened and all but 1/4 cup of the liquid has been absorbed, 20 to 25 minutes. Boil, uncovered, to reduce any excess liquid.
Cool the figs in the liquid; then strain, reserving 1/4 cup of cider syrup. Set aside 8 whole figs. Using kitchen scissors, trim the stems from the remaining figs and cut them into 1/2-inch pieces.
Heat 2 tablespoons of the olive oil in a large skillet. Add the onions and apples and cook, stirring, over medium heat until the onions are golden, about 15 minutes.
Add the garlic, 1/2 tablespoon of the sage, and salt and pepper to taste. Cook for 1 minute.
Stir in the cut-up figs. Set aside to cool.
Preheat the oven to 350ºF.
Cut eight 18-inch lengths of cotton string. With a thin sharp knife, cut the pork lengthwise down the center, about three-quarters of the way through, so it can be opened like a book. Season the opened pork with a sprinkling of salt and a grinding of black pepper.
Spoon about half of the apple-fig mixture in a thick layer over the bottom portion of the pork, spreading it evenly. Fold the top portion of the pork over the bottom.
Slide the strings under the pork, evenly spaced, and tie them firmly but not too tightly. Tuck any stuffing that escapes back into the roast.
Rub the remaining 1/2-tablepooon sage and a generous amount of salt and pepper over the outside of the pork.
Heat a Dutch oven or other large, heavy ovenproof pan over medium heat until it is hot enough to sizzle and evaporate a drop of water. Add the remaining 1 tablespoon olive oil.
Add the pork and sear it on all sides until golden brown, about 2 to 3 minutes per side. Remove the pan from the heat, and spoon the remaining apple-fig mixture around the pork.
Place the pan in the oven and roast, uncovered, for 15 minutes. Remove the pan and carefully turn the roast over.
Roast until a meat thermometer inserted in the pork registers a temperature of 135ºF, 10 to 15 minutes more. (The internal temperature will rise as the pork rests out of the oven.)
Remove the pan from the oven, transfer the roast to a cutting board, and tent it with foil to keep it warm. Spoon the apple-fig mixture into a serving dish and cover to keep it warm.
And the remaining 1 cup apple cider, the wine, and the reserved 1/4 cup apple cider syrup to the pan. Heat to a boil, scraping the browned bits from the bottom of the pan. Boil until the mixture is reduced to about 1/2 cup, about 5 minutes. Taste and add lemon juice if desired, and salt and pepper if needed.
Cut the meat into 1/2-inch-thick slices and arrange them, slightly overlapping on a warmed platter. Spoon the apple-fig mixture around the edges, and garnish with the reserved whole figs and sage leaves. Spoon the cider sauce over the meat, and serve.
* A well-trimmed boneless pork loin has had the log narrow strip of meat called the tenderloin removed. The resulting roast measures only about 3 to 4 inches in diameter and 12 or more inches long. This is the cut that is required for this roast.