Season the flour with salt and pepper on a plate. Coat the pork with the flour.
Heat 2 tablespoons of the oil in a large flameproof casserole and fry the pork in batches until browned on both sides, lifting out with a slotted spoon on to a plate. Add the remaining oil to the casserole and gently fry the onions, carrots and celery for 10 minutes until softened. Add any flour left over from coating and cook, stirring, for 1 minute.
Blend in the wine and bring to the boil, stirring. Stir in the tomatoes, tomato paste, stock and a little salt and pepper. Return the pork to the casserole, cover and cook in a preheated oven, 160°C (325°F), Gas Mark 3, for 1½–2 hours until the meat is very tender.
Mix together the garlic, lemon rind and parsley and sprinkle over the casserole and serve.