1) Warm the cognac and water in a small saucepan, add the cranberries and apricots, and set aside until plump, about 10 minutes. In a small food processor, pulse the fruit and any unabsorbed liquid with the almonds, shallot, butter, fennel seeds, 1/2 teaspoon salt, and pepper, to taste, until the fruit and nuts are coarsely chopped.
2) With a boning knife or other long, thin knife, make a cut 3 inches across in the center of one end of the roast. Gently push and work the blade in and straight through the roast to the other end. (If your knife is not long enough, make a cut at either end and work your way to the center, making sure that the cuts meet.)
3) Insert the narrow end of a wooden spoon into the opening to widen it all the way through. Push the stuffing into the loin, working first from one end and then the other, filling to the center.
4) Preheat the oven to 180C/Gas 4.
5) Pat the loin dry and season all over with salt and pepper. Heat the oil in a large ovenproof skillet over medium-high heat. Add the roast, holding the bones up so that the bottom gets well browned, then turn the roast to brown the meaty side, about 6 minutes total.
6) Transfer the skillet to the oven and roast the pork meat side down for 30 minutes. Turn the roast over so it sits on the bones and roast until an instant-read thermometer inserted into the center of the meat registers 68C, about 1 hour more.
7) Transfer the roast to a carving board, tent loosely with foil, and let it rest for 10 minutes before carving.
8) Whisk the creme fraiche or sour cream with the mustard in a small bowl and season with salt and pepper, to taste. Slice roast between the bones to make individual chops, arrange them on a platter, and serve, passing the mustard sauce.
Know-How: Roasting meat on the bone keeps meat moist and improves its flavor. Pan-searing before roasting is the way to get a great burnished crust on lean meats that would otherwise dry out if left to brown solely in the oven.