Patak's is good, but not much less work than putting the spices in yourself. I found a recipe off the Internet years ago and have been using it ever since. Fry onions in some oil, add ginger and garlic fry some more, add spices and dry fry then add meat and fry further. Add tinned tomatoes and some yoghurt and slow cook for a few hours. Serve with some fresh coriander on top.
Easy.