Heat the oil in a wok or large frying pan, then add the cardamoms and cassia bark. Fry for 1 minute.
Tip in the onions and fry for 1 minute.
Add the beef, followed by the chilli and garlic and fry on a medium heat for 4 minutes.
Then add the turmeric, salt, cumin and coriander and stir for another minute.
Mix the tomato purée with 150ml/5fl oz of hot water (double this amount if you want more sauce) from the kettle and add to the pan. Cook for 3 minutes.
Mix in the ginger and sprinkle over the garam masala and the coriander leaves.
Serve immediately with a naan or in hot pitta breads.