Melt the butter over low heat and cook onions until translucent, and then remove the onions from heat. Fold in the bread crumbs, apples, raisins, orange zest, and caraway, and season with salt and pepper.
Preheat oven to 400 degrees F.
Cut a pocket into the pork loin between the meat and outer layer of fat, the pocket should be shy of reaching each end of the loin by one inch. Fill the pocket with the stuffing. Roll loin up lengthways closing the stuffed pocket and tie with a string. Score the rind of pork with a sharp knife.
Whisk together cider and sour cream and place in a casserole equal to the size of the pork. Place pork in casserole rind side down and bake for 30 minutes.
After 30 minutes turn pork over and cook, rind side up, for another 30 minutes.
Reduce heat to 350 degrees F and cook for another hour (baste every 20 minutes with the pan juices) or until you reach a internal temperature of 150 degrees F. Let rest for 20 minutes. Deglaze the roasting pan with 2 ounces white wine and season. Slice the meat and serve with the jus.