Heat 1tbsp oil in a saute pan, add mustard seeds and cumin seeds. Once the seeds start to splutter, add curry leaves and green chilies (if using). Cook for 1 minute.
Next add the bottle gourd pieces, turmeric and salt. Mix well, cover and cook till bottle gourd is tender, about 10~12 minutes. Alternately bottle gourd can be par cooked in the microwave for 4~5 minutes and then added here and cooked for 4~5 minutes more.
Finally add the ground coconut paste, mix well and cook for another 4~5 minutes. Add more water if the curry looks too dry. Serve with steamed rice and dal.