Put the ginger, garlic and onions in a food processor and whizz to a paste. Heat 1 tbsp oil in a pan then add the paste, green chillies and half a tsp salt and cook for 3-4 minutes until fragrant. Add all the spices and cook for a couple of minutes. Add the lamb and keep cooking and stirring until browned. Stir in the tomatoes, tomato purée and a cup of water then bring to a simmer. Cover and cook for 1 hour. Add the spinach then cook for another 15 minutes. Serve with rice or Indian breads.