Wash water convolvulus thoroughly and drain in a colander. Pluck the leaves and discard tough fibrous stems.
To make batter, sift both kinds of flours and baking powder into a mixing bowl.
Add sugar, pepper and chicken stock powder. Make a well in the centre and gradually blend in water until batter is smooth. It should be slightly thick. Dip the water convolvulus leaves one or two at a time into the batter.
Deep-fry in hot oil for less than a minute or until golden and crispy.
Drain on absorbent paper and arrange the battered vegetable on a serving dish.
Serve hot with chilli sauce if desired.