Take Besan in a bowl, add rice flour, salt, ajwain, ginger, red chilli powder, baking soda and green chilli to it.Mix the ingredients together and add coriander leaves.
Now make a batter of these ingredients by adding water and stirring it together. Keep stirring until it turns into a thick batter.

Take some oil in a pan, dip onion slices completely into the batter and fry in the pan

Deep fry until they turn crisp and golden brown.

Serve hot with tomato ketchup.