Heat the oil in a large saucepan and fry the diced pork until browned. Add the onions, paprika and caraway and fry gently for a further 5 minutes until the onions are browned.
Add the piece of bacon knuckle, the bay leaves and measurement water. Bring to the boil, cover with a lid and reduce the heat to the lowest setting. Cook very gently for about 2 hours until the bacon knuckle is very tender and the meat falls easily from the bone.
Drain the knuckle to a plate and leave until cool enough to handle. Pull the meat from the bone and shred it back into the pan, discarding the skin and bone.
Add the beetroot, cabbage and tomato purée to the pan and cook gently, covered, for about 15 minutes until the beetroot and cabbage are tender. Check the seasoning and serve.