1) Combine the plain flour, rice flour, salt, white pepper, chilli powder and Chinese five spice in a bowl.
2) Preheat oven to 160°C. Line a baking tray with 5 layers of paper towel. Place the oil in a large saucepan or wok. Heat to 190°C over medium heat (when the oil is ready a cube of bread will turn golden brown in 10 seconds).
3) Place one-quarter of prawns in the flour mixture. Toss to coat. Shake off excess. Add to the oil and cook, stirring, for 1 minute or until golden. Use a slotted spoon to transfer to the lined tray. Place in oven to keep warm. Repeat, in 3 more batches, with flour mixture and remaining prawns, reheating oil between batches.
4) Add the coriander to the oil and cook for 10 seconds or until crisp. Transfer to a plate lined with paper towel. Place prawns on a serving platter. Top with coriander. Serve with lemon wedges.