Tip the pork into a bowl and stir in the curry powder and vinegar. Set aside. Heat the oil in a heavy-based pan and fry the onion and ginger for 10 mins, stirring frequently, until golden. Tip in the pork mixture and fry for a few mins more. Remove the pork and set aside. Stir in the toasted spices, then tip in the tomatoes, lentils and aubergine, and crumble in the stock cube. Cover and leave to simmer for 40 mins, stirring frequently, until the aubergine is almost cooked. If it starts to look dry, add a splash of water. Return the pork to the pan and cook for a further 10-20 mins until the pork is cooked and tender.