Method

1. Arrange the frozen potato rostis or hash browns in a single layer on a large baking tray so that they can start to thaw as you make the pie filling.

2. Heat a large, non-stick saucepan over a medium heat. Add the onion and lamb mince and fry for 8-10 minutes, stirring regularly, until the lamb is no longer pink. Sprinkle over the curry powder and flour and stir well.

3. Add the tinned tomatoes, tomato purée, water and herbs to the pan and stir well to combine. Crumble over the stock cube, stir again, and season, to taste, with salt and freshly ground black pepper.

4. Bring the mixture to the boil, then reduce the heat until the mixture is simmering and simmer for 8-10 minutes, stirring regularly, until the mixture has thickened.

5. Meanwhile, preheat the oven to 200C/180C Fan/Gas 6.

6. Once the filling mixture has simmered for 10 minutes, stir in the frozen mixed vegetables and remove the pan from the heat. Transfer the mixture to a 1.7 litre/3 pint pie dish.

7. Break the thawed rostis or hash browns into smaller pieces and scatter them over the shepherd's pie filling.

8. Transfer the pie dish to a baking tray, then cook in the oven for 25-30 minutes, or until the potato topping is cooked through and the filling is bubbling. Garnish with fresh coriander just before serving, if desired.