Toast all curry powder spices except turmeric in a dry pan until fragrant.
Grind toasted spices and turmeric into a fine powder using a pestle and mortar.
Brown the lamb cubes in one tablespoon of oil in a wok and set aside.
Fry onion, ginger, garlic, curry powder, and chilli powder in remaining oil for two minutes.
Add lamb, salt, saffron water, cashew paste, and cinnamon stick to the wok.
Cover with water, bring to boil, and simmer for 75-90 minutes until lamb is tender.
Stir in the yoghurt and tomatoes and simmer for two more minutes.
Serve the lamb curry over cooked rice garnished with coriander leaves.