Preheat the oven to 170C/325F/Gas 5.
Mix the garlic and the rosemary together in a bowl. Using a small knife, make holes in the outside of the pork, and stuff a little of the garlic and rosemary as deeply as you can into each one.
Pour the wine into a roasting tin large enough to hold the pork. Place the pork in it, bones downwards so that they form a support for the meat itself.
Rub the skin with the extra virgin olive oil, season and roast for two hours, basting occasionally with its own juices. Add a few good splashes of water to the pan every time you baste so the juices do not dry out and burn. To check that it is cooked, plunge a skewer into the centre (not too near the bone) and pull out - if the juices run clear, then it is ready. Leave the pork to rest in a warm place (you can simply turn the oven off and leave the door ajar) for about 20 minutes.
To carve, use a sharp knife and cut down close to the ribs, sliding the knife underneath the meat, until you reach the long, solid chine bone at their base. Swivel the blade of the knife upwards and guide it over the chine bone and down the other side, to release the meat. Lift the meat off and cut into slices about 2.5cm/1in thick.
Arrange the meat on a plate, cover and keep warm.
Quickly put the roasting tin over the heat and bring to the boil, scraping in all the residues on the base and adding a little more water if they taste too strong.
Pour into a jug and serve.
For the cannellini beans, heat the oil and gently fry the garlic and sage leaves. When the garlic is golden brown, add the beans and season generously.
Add the sieved tomatoes or passata, the tomato purée, and about one teaspoon of caster sugar, to taste.
Simmer gently for a further 20 minutes or so, stirring occasionally to prevent catching.
Check and adjust the seasoning just before serving.