Add the oil to a frying pan, and fry the lamb over a medium-high heat for 5 minutes until browned.
Add the onions, minced garlic, and minced ginger and fry for a further 10 minutes until the onions have softened.
Transfer the contents of the frying pan to the slow cooker, add the bone and all remaining ingredients, except for the yoghurt and tomatoes.
Stir gently to combine, and cook on high for 3.5 hours, or low for 7 hours.
Stir in the yoghurt, and add the tomatoes. Continue to cook on high for another 30 minutes.
Remove the bone, garnish with coriander leaves to serve, and enjoy!