In a bowl, add besan flour, rice flour, salt, asafoetida, chilly powder, red color and baking soda mix well.
Add enough water mix well without lumps and make a thick batter.
Heat oil in a pan.
Cut onion into thin round slices.
Take an onion slice and dip it in the gram flour batter. Coat the batter well on all sides of the onion.
Drop it into the hot oil.
Deep fry both sides until it cooks well.
Onion bajji is ready to serve with hot tea.