First of all, add gram flour in a mixing bowl.
Add 1/2 cup of water and whisk it to a smooth batter. Keep this aside for 10 minutes.
Now add salt, Chilli powder, turmeric, roasted cumin powder, chaat masala and carom seeds and mix well.
Add chopped onion, tomato, green chilli and coriander leaves and mix it well. Now with the help of a ladle, check the flowing consistency of batter. If it's thick, add little more water and whisk.
Heat a non stick tava on medium flame and pour a ladleful of batter in the centre and spread gently in circular motion like normal dosa / pancake.
After one minute, spread little oil all over it and let it cook for 2-3 minutes, so that it is cooked well.
Flip it over and let it cook for 2 minute from this side too.
Take it out and serve it hot.