In a large, deep frying pan with lid, add the butter/ghee and melt over medium-high heat. Meanwhile, combine all spices in a small bowl and mix with a fork to break up any lumps.
Add the onion, capsicum and garlic paste and saute for 2 minutes until the onion is just translucent, being careful not to burn the garlic.
Add the diced lamb and fry, turning constantly to brown on all sides.
Once the lamb is just brown, add the spice mix and toss to coat the meat evenly. Cook for 1 -2 minute until fragrant.
Add the tinned tomatoes, chicken stock and juice from half a lemon and stir to combine.
Cover, turn heat to low and simmer for 20 minutes. Meanwhile, in a small bowl, combine the plain yoghurt and mint.
Remove the lid and simmer for a further 20 - 25 minutes until the sauce is thickened to your liking and lamb is tender.
Serve with cauliflower rice, fresh coriander and mint sauce.