Cut the onions into rings about ¼ of an inch thick and separate them from each other carefully. Set aside the smaller ones for other recipes.
Combine the flour, baking powder, baking soda, red chilli powder, salt in a medium bowl.
Add curd little by little and also water to make batter. Mix well until no lumps remain.
Heat oil in a deep bottomed pan.
Coat each onion ring in the batter and shake away the excess.
Coat in bread crumbs and fry them in the oil under medium flame.
Transfer them to kitchen towel to get rid of the excess oil.
Serve hot with tomato sauce.