Heat a pan in full flame, add oil (mustard), half spoon cumin seeds, onion chopped saute for some time till it turns brown, tomatoes chopped, add salt to taste, turmeric powder, red chilli powder, coriander powder and saute well, close the lid for 5 min in low flame. Add the small cubes of bottle gourd and mix it up well, put in slow flame around 15-20 min.