Heat half the oil in a large saucepan over high heat. Cook pork, in batches, until browned. Add more oil if needed. Remove to a plate.
Add onion to saucepan. Cook, stirring, for 3 minutes. Add garlic, ginger, chilli, mustard seeds and curry paste. Cook for 1 to 2 minutes until mustard seeds pop.
Return pork to saucepan with water and vinegar. Simmer, covered, for 60 minutes or until pork is tender.
Serve with basmati rice and raita (yoghurt and cucumber dip), if desired.
