Warm the oil in a frying pan over a medium heat. Add the onion and cook and stir until softened.
Turn the heat up a little and add the lamb to brown for a minute or two, stirring continuously. Add the garlic to the pan with the curry powder. Add the lamb stock and tomato, stir well and bring to simmer. Put the lid on and simmer over a medium heat for 10 to 15 minutes (add a little more stock if the mix becomes too dry).
Turn the heat up and add the rice to the pan, cooking for 2 to 3 minutes until warmed through. Stir in the fresh coriander and mint then serve.