Lamb keema with rosti topping

Method

1. Heat 2 tbsp of the olive oil in a wide medium saucepan over a medium heat. Add the chopped onion, season well and fry until softened. Add the finely chopped garlic, grated ginger and green chillies and fry for 2-3 minutes more.
2. In a separate frying pan, dry-fry the cumin and coriander seeds until fragrant, then crush in a pestle and mortar with the turmeric and chilli powder until finely ground. Add to the onion mixture and fry for about 1-2 minutes.
3. Add the mince, turn up the heat and fry for 10 minutes until golden. Drain off the excess fat. Add the lamb stock and vine tomatoes to the saucepan, bring to the boil, cover and simmer for 30 minutes until the lamb is cooked and the sauce has thickened slightly.
4. Put the spinach in a colander, pour over a kettle of boiling water, then refresh in cold water. Squeeze out the excess water. Stir through the curry with the lemon juice and garam masala, and season to taste.
5. Place the potato, sweet potato and onion in a pan of boiling salted water and blanch for 30 seconds. Drain, then tip into a clean tea towel and squeeze out all the excess liquid. Place in a bowl, toss with the remaining olive oil and season.
6. Tip the keema into a 1.8-litre freezerproof dish and top with the blanched rosti topping.