Heat 1 tbsp oil in a very large casserole or heavy based saucepan. Add the pork and cook until well browned all over (if the meat is too large to fit inside the pan, cut into 2 or 3 large pieces before cooking). Remove the pork from the pan and add the onion. Leave to cook for 5 minutes, until just soft. Stir the paprika into the onion then return the pork to the pan, along with the tomatoes and stock. Bring to the boil, then cover the pan, reduce the heat to very low and leave to simmer, turning the pork occasionally, for 3 hours or until the meat is very tender. Remove the meat from the pan. When cool enough to handle, use a fork to tear into shreds, discarding any fat or skin. Meanwhile, add the peppers and beans to the pan and leave to simmer for 20 minutes. Return the shredded pork to the pan and cook together for 10 minutes. To make the gremolata, mix together the garlic, orange and parsley. Spoon the pork stew onto serving plates and scatter over the gremolata to serve.