In a heavy-bottomed pot, add meat, ginger, garlic, onion, tomato sauce, salt, chili pepper, turmeric, black cardamom pod and 250ml (1 cup) water. Stir, cover and leave to cook on a low-medium flame for one hour.
Stir/check every 20 minutes to make sure the meat is not sticking to the bottom of the pot.
After an hour you will note that the liquid would have reduced significantly and the oil has floated to the top of the meat. Skim this oil off with a spoon.
Turn the heat to medium-high / high. Stir the meat rigorously for 10 minutes (in Urdu, this procedure is called 'bhun-na') till the liquid has completely evaporated and the meat turns darker. The onions and garlic cloves will be completely soft and incorporated into the mince meat by this point. Be careful not to let the mince meat stick to the bottom of the pan, if it does, lower the heat.
After ten minutes of stirring, add 250ml (approx 1 cup) of water and potatoes and reduce heat to medium.
Cover and allow potatoes to cook for 15-20 minutes. Check potatoes for doneness after 10 minutes by inserting a knife. When potatoes are done, remove lid, turn heat to medium-high and allow liquid to evaporate.
Mix in fresh chopped coriander or desired herb.
Spoon approximately 2tbsp of mince meat onto bun, add your favourite condiment and eat immediately.
Alternatively, enjoy with basmati rice, chapati, naan or even a baguette when that's all you have in the house.