For the pork knuckle, preheat the oven to 120C/100C Fan/Gas ½. Make 5 small deep slits between the skin and flesh of the knuckle of pork using a sharp knife, and stud each slit with a whole clove of garlic. Rub the skin all over with the honey. Place in a casserole dish and add the red wine, olive oil, salt and pepper, peppercorns, bay leaf, cinnamon stick, coriander seeds and 75ml/2½fl oz water. Cover with a lid and bring up to a simmer on the hob, then transfer to the oven and bake for 4-4½ hours until the meat falls away from the bone.
While the pork is cooking, fry the onions gently in olive oil for 5 minutes over a medium heat, then add the salt and 100ml/3½fl oz water, cover with a lid and cook gently for 25 minutes.
For the tomato garnish, very gently cook the tomato halves in a clean pan with the olive oil over a medium heat for about 2 minutes until softened. Season with the salt and pepper.
Serve the pork knuckle with the slow-cooked onions and tomatoes.