Preheat the oven to 220°C. Heat the oil in a large frying pan over a low heat. Add the spring onions and half the garlic and cook for 2 minutes, stirring frequently. Add the capsicum, increase the heat to moderate and cook for 5 minutes, stirring until the capsicum is just tender.
Add the lamb and spices and cook for 2–3 minutes, stirring occasionally to break up the meat, until it is no longer pink. Stir in the tomatoes, stock and kidney beans and bring to the boil. Reduce the heat to a simmer, cover and cook for 15 minutes until the mixture is thick.
Meanwhile, cook the potatoes with the remaining garlic in a saucepan of lightly salted boiling water for 10 minutes, or until tender. Drain the potatoes, reserving 50 ml of the cooking liquid. Return the potatoes and garlic to the pan with the reserved liquid and crush them using a potato masher or large fork. Stir in the chopped coriander.
Spoon the lamb mixture into a deep pie dish, about 1.5 litre capacity. Spoon the crushed potatoes over the top. Bake for 15 minutes until golden. Serve hot.
• This dish can be assembled ahead of time up to the end of step 3, then baked for 15 minutes, or until heated through, before serving. * • Alternatively, you can use lean minced beef and tinned beans if you prefer.