Garam Masala - If you are using a store brought version, the flavour can vary quite a lot. So add a little and taste before adding more. Alternatively use a good Curry Powder like Madras Curry Powder.
Meat - You can also use Lamb Leg, Mixed Lamb, Beef to Mutton in this recipe. The meat is cooked over low heat for a long time here. You can add water to the pot midway but I prefer not to.
Potatoes - Adding the potatoes is optional. It is absolutely delicious without them because the addition of them mutes the flavours slightly but..my kids like them so they had to go in! If you choose not to add them, add the Garam Masala and Green Chillies (N0 water) and cook for 3 - 4 minutes.