Heat the oil in a large pan. Add the onion and cook for a few minutes to soften. Add the tomato pureé, stir for 1 minute, then add the lamb mince. Cook for 5 minutes until the meat is nicely browned all over.
Stir in the curry paste, chopped tomatoes, sweet potato and butternut squash. Fill the empty tomato carton up halfway with water and add this to the pan. Season well, then cover with a lid and simmer for 15 minutes.
After 15 minutes, add the trimmed okra and allow to simmer for a further 10 minutes or until the sweet potatoes are nearly cooked.
Remove the lid and simmer for a further 10-15 minutes until the liquid has reduced and the sauce clings to the potatoes and mince.
Heat the naan. Serve with a spoonful of the curry, yogurt and a sprinkling of roughly chopped coriander and pomegranate seeds.