This is a great curry and pretty easy to make. You can use chicken in place of lamb, however you choose, it always tastes good. You can make it in advance and reheat it and it's great for freezing.
Heat the oil in a saucepan, add the onions cook untill they start to brown. Add the garlic and tomatoes stir for about a minute.
Add the chilli powder, turmeric, cumin and salt to taste and stir.
Stir until the oil starts to separate out, if it starts to catch on the bottom of the pan, add a tablespoon or two of water.
Add the lamb and 200ml of water. Place the lid on and leave on a low heat to cook 30 minutes. Add the spinach replace the lid and continue cooking for 15 minutes or untill the lamb is tender.
Remove lid and simmer for a further 10 to 15 minutes or until the excess liquid has evaporated and the oil separates out.
Garnish with chopped green chillies and slivers of fresh ginger and serve with a rice of your choice.