1. Cook the onion, garlic, 1/2 teaspoon of the rosemary, and 1/2 teaspoon of the thyme in the butter and oil in a skillet until the onion has softened. Add the apple pieces, brown sugar, salt and pepper and cook for a few minutes until the apples have lost their raw look but are not yet fully softened. Stir in the prunes and remove from heat.

2. Preheat the oven to 425F. With a long sharp knife, cut a small pocket down the enter of the pork loin, stopping 1 inch from the end. Set aside 3/4 cup of the apple-prune stuffing and stuff the rest into this pocket and under the flap of meat that wraps around the outside of the roast. Don't worry about everything looking perfect; just get as much stuffing into the roast as possible. 

3. Mix the remaining rosemary and thyme with the garlic powder, sage and a liberal amount of salt and pepper. Rub this mixture all over the surface of the pork and set the meat, fat side up, on a rack in a roasting pan.

4. Roast for 40 minutes. Pour 1 1/2 cups of the apple cider over the meat and reduce the oven temperature to 350F. Roast, basting occasionally with the liquid in the pan, for another hour to hour and 15 minutes, until a meat thermometer inserted into the thickest part of the meat (not the stuffing) registers 160F. Transfer to a platter.

5. Pour the liquid from the pan into a large measuring cup, skim the fat from the surface, and save the fat in a separate bowl. Add enough of the remaining apple cider to the defatted liquid to equal 3 cups. Pour the mixture into a saucepan and add the fresh rosemary. Bring to a boil. Meanwhile, mix the flour with 2 tablespoons of the reserved skimmed fat. When the liquid boils, whisk in the fat-flour mixture and simmer until the sauce thickens lightly. Stir in the reserved apple-prune stuffing. Adjust the seasonings to taste and serve alongside the meat.