Put the flour, baking powder, chilli powder, coriander, chilli, turmeric, and onion in a large bowl.
Season with salt and mix together with enough water to make a thick batter.
Heat enough oil for deep-frying in a kadhai or deep, heavy-based pan to 180 degree C / 350 degree F, or until a cube of bread browns in 30 seconds.
Working in batches, drop spoonfuls of the batter into the hot oil and deep-fry for 3-4 minutes, or until golden brown.
Remove from the heat with a slotted spoon and drain on a crumpled up kitchen paper (paper towels).
Serve plain.