Here goes the recipe:
Parboil 4 medium size potatoes in water adding salt. Do not overcook the potatoes. cube them. Deep fry the cubed potatoes in mix of oil and ghee(1/2 and 1/2) to golden brown. Transfer all the oil into a cup and heat say 3 tbsp of oil ghee mix, to this add coriander, cumin, chilli powder and garam masala powders(1 tbsp, 1/2 tbsp, 1 tbsp or more-suit your spice level, a pinch respectively). Do not brown them add 2 cups of water and required salt. Allow it to boil for 5 mts. Add the fried potatoes to this. Cook this on a medium flame for 5 mts and simmer to reduce.
You may go wrong at these places: 1. over cooking the potatoes resulting in a soggy curry 2. browing the masalas resulting in a bitter curry
If taken care you will end with a delicious dish.