Remove fat from meat, if any. If the meat is large, cut it to fit in the slow cooker. In a small bowl, combine the apple cider vinegar (juice), horseradish, soy sauce, and spice mixture. Place the meat in a slow cooker and pour the apple sauce over the top. Close the slow cooker and cook on low power for 10-12 hours or on high power for 5-6 hours.
Put the pork on a cutting board, let it cool slightly, then remove the bone, and tear the meat into pieces and put in a bowl, add the cabbage inflorescences, mix.
Cut the buns into halves and stuff them with the meat mixture. Pour the juice from the slow cooker into a saucepan and serve with the burgers.