'Singhada', the 'Indian Water Chestnut' is green outside and white inside. It is very juicy and crunchy, when eaten raw and very rich in vitamins.
It is sold by hawkers on pavements raw and also steamed. When steamed, it's rind becomes coal black and it tastes somewhat like a potato.
Singhada is peeled, dried and crushed to get flour 'singhade ka atta' which is used to prepare 'pooris' and 'rotis' for fasting.