Preheat the oven to 340 F. Fry the onion in butter for 5 minutes and then add the garlic. Fry everything together for 2 minutes on low heat. Add chopped apples to the pan with onions. Stir and fry everything together for another 6-7 minutes, or until the apples are soft.
Add about 1/2 cup of broth, as well as 1/2 of the salt and spices. Stir. After another 5 minutes, the apples will become very soft and almost all the liquid will evaporate. Remove from heat.
Gently cut the pork (not all the way through) to form slices about 1/2-inch thick so that they can be spread with the stuffing and rolled up. Salt the pork with the remaining salt, and add spices and herbs. Spread the layers of pork with the apple filling. Roll so that all the filling is inside. The skin will be on the bottom.
If you want to ensure it doesn't roll up, set 3 pieces of baking twine on cutting board, on that will be on top, middle and bottom of the roll. Set filled roll on top and tie to secure.
Place the pork skin side down in a roasting dish. Pour in broth. Cover the roasting dish with foil (or a lid) and place in the oven. Bake for 60 minutes.
Remove the foil, increase the temperature to 400 F and bake for another 15 minutes. Ensure internal temperature is at 145 before removing. After this, remove from the broth, allow to rest for 10 minutes, cut into slices and serve.