Place flours and baking powder into a large bowl. Add egg and chilled soda water. Stir until just combined (do not over-mix, this mixture doesn't have to be smooth)
Heat the oil in a wok until when tested with a small piece of bread, it sizzles when dropped into oil
Dip the prawns and pear, one piece at a time, into tempura batter, allowing excess to drain
Gently lower into hot oil. Cook, 3 to 4 at a time, for 2 to 3 minutes, or until batter is crisp and light golden. Drain on paper towels. Repeat until all pear and prawns are cooked
Serve immediately sprinkled with sea salt flakes and a bowl of soy sauce for dipping
