Heat a couple of tablespoons of oil in a pan and sear the pork belly pieces, turning it around on all sides.
Add the chopped onions and fry for a couple of minutes.
Pour the wine on top, and wait for the alcohol to evaporate.
Add the chopped tomatoes, a little bit of water if it needs it, and the bay leaf, put the lid on, and let everything simmer for around 30 to 40 minutes – or until the meat is tender.
Meanwhile, prepare the cabbage.
Shred the cabbage and rub it with salt, leaving it in a bowl until the meat is tender.
Once the meat is done, add the chopped carrot and the pepper.
Add the cabbage to the pan, together with the caraway seeds and the thyme.
Mix well, put the lid on, and let it simmer for another 20 minutes or so.
Mix from time to time, to avoid the cabbage sticking to the pan.
Taste and season with more salt if it needs it (shouldn't do) and pepper.
Serve alongside polenta, topped with sour cream.