Cut the onion in half through the stalk. Put the flat side down on the chopping board, starting at one end cut thin slices until you reach the other end.
Sift the flour and baking powder into a bowl.
Add the salt, turmeric, chilli powder, garlic and ginger and mix.
Add the water; you need a thick batter (double cream consistency).
Stir in the onion.
Heat the oil; a drop of batter should sizzle as soon as it hits the oil.
Place tablespoon sized amounts into the oil; be careful not to overload.
Leave to cool on a baking tray.