Punjabi Tinda sabji

How to make punjabi tinda you will need 1kg Tinda 2 small potatoes (optional) 3 med onions 3 tbs oil 1tbs ghee or butter 3 med onions 1tsp salt Half tsp haldi powder (turmeric) 1tsp kashmiri chili powder 1tsp whole cumin 2 tsp garlic 2 tsp ginger 3 fresh chillis 3 tomatoes 1 tsp coriander powder Half tsp gram masala 1tsp kasoori methi (dried fenugreek) fresh coriander