Trim any excess fat of the lamb pieces. Heat 1 tbsp of the oil in a large casserole dish and brown the meat (do in batches if necessary). Remove the meat and drain the fat from the pan. Heat the remaining 1 tbsp of oil over a medium heat and cook the onions, garlic, ginger and spring onions gently for 5 minutes. Add the Poudre de Colombo and mix well. Fry for 1 minute until fragrant.

Return the meat to the dish along with the thyme, stock and tomato paste. Bring to the boil, then gently simmer for 1 hour until the meat starts to be tender. Adjust salt and pepper seasoning and add the potatoes and squash and continue to cook until for up to another hour. The meat and vegetables should be well done by this stage. Add more stock during cooking if necessary.

Stir in the lime juice just before serving and scatter with fresh coriander if using.