Sieve the chickpea flour and add the salt, bicarbonate of soda, ground rice flour, cumin, coriander, chili powder and green chilies. Mix well. Gradually add the water and keep mixing until a thick batter is formed. Refrigerate for at least 15 minutes.
Loosen the onion half rings and stir into the batter.
Heat the oil in a wok to 180 degC.
Using tongs, grip a batch of the onions and place into the hot oil. Keep adding more onions but do not overfill the wok.
Cook for approximately 8 minutes or until the batter is brown.