Cut the pancetta into short, thick lardons (about the size of a little finger), then put them into a large, heavy-based saucepan over a low-to-moderate heat and let them cook for 7-10 minutes until the fat turns golden. If the pancetta is unusually lean, use a tbsp or two of oil.
Peel and roughly chop the onions, then stir them into the pancetta and its fat, adding a little oil if necessary and let the onions cook for about 15-20 minutes until soft and pale gold.
Chop and stir in the rosemary.
Peel and thinly slice the garlic, then let it cook with the onions.
Peel the ginger and cut it into thin coins, then stir in together with the star anise.
Heat the oven to 180C/gas mark 6.
Fry the pork on both sides untll the fat is golden, then remove and tuck the pork among the onions.
Drain the butter beans and add to the pork and onions.
Pour the sherry into the shallow pan, turn up the heat and let it bubble, stirring any tasty caramelisation left behind by the pork.
Pour in the stock and bring to the boil.
Pour the stock and sherry mixture into the pan with the pork and onions, pour in the rice wine and soy sauce, a little salt and some black pepper, cover with a lid and bake for about an hour until the pork is tender but not falling apart.
Serve in shallow bowls or deep plates.
