Combine batter ingredients in a mixing bowl. Stir and mix into a smooth batter. Add fish slices, onion, chilli and spring onion into the batter. Mix well. Heat enough oil in a wok until hot. Scoop a slice of fish together with the ingredients in the batter.
Drop it into the hot oil. Deep-fry until golden brown. Dish out and place on absorbent kitchen paper towels. Serve the fritters immediately with chilli sauce.