Preparing the bottle gourd
Peel the skin of your bottle gourd with a peeler. Cut the long bottle gourd into 4 smaller segments.
Keep a bowl of water on the side and put the segments in the water.
Take out one segment of the bottle gourd and cut it into 4 wedges (length wise). Now the fleshy center of the gourd will be visible to you.
Check for seeds of the gourd, if they are very big, slice the central part of the gourd with all the seeds. Small seeds can stay.
Now thinly slice the gourd wedges into triangular chips. You can do this manually with a knife. You can also use a mandoline or a food processor with the slicer attachment to do this step. Keep putting all the sliced chips in water to prevent them from turning brown.
Cooking the gourd
Add oil in a wok or a pot along with sliced onions, chopped garlic and cumin seeds at medium flame
Saute the onions till they turn translucent.
Add turmeric, crushed red chili and red chili powder. Saute for another 2 mins at low medium flame.
Add in chopped tomatoes and mix.
Drain water from the gourd and add it to the pot. Stir everything together so that all the sliced gourd gets coated with all the spices. Cover the pot and let it cook at medium flame.
Allow the gourd to cook for 20 to 25 mins or till the all the water from the vegetable evaporates.
Once you see oil separating on the side, reduce the flame to low. Add salt and mix well. Add green chilies and chopped coriander. Cover the pot again and let it simmer for another 4 mins at low flame.
Turn off the flame and serve with rice and lentils.