Peel and slice the onions into rings. Peel and slice the garlic lengthways. Lightly crush the coriander seeds with a pestle and mortar.
Heat the oil in a large saucepan over a medium heat. Cook the pork in batches, stirring occasionally, until browned (5 to 7 minutes), adding a little more oil if necessary. Transfer to a bowl and set aside.
Add the onion, garlic and coriander seeds and cook, stirring occasionally, until softened.
Return the pork to the pan, stir in the wine and passata, season with sea salt and black pepper, cover with a folded piece of baking parchment, bring to the boil, then simmer for 1½ to 2 hours, or till the pork is tender and sauce has thickened.
Serve with boiled orzo or rice, and sprinkle with freshly grated kefalotiri or Parmesan.