Make several small incisions in the belly of the prawn tail straighten the prawn by stretching the flesh into a longer even shape.
Combine flours together and slowly add soda water while whisking together. Add enough soda water until a it forms a batter that holds its form on your finger when dipped. Keep chilled in the fridge or on ice.
To pickle carrot and papaya, whisk sugar with water until sugar dissolve, add vinegar and then add carrot papaya julienne. Keep it in fridge, ready to use after 1 hour.
Holding the tail, dip prawns into the in fish sauce, then with rice flour, dip in tapioca batter, and then cover in green rice flakes.
Deep fry prawns at 180°C/ 356° F for 1 min 30 seconds drain the prawns thoroughly on absorbent paper tray with paper.
Serve the prawns with butter lettuce, herbs, pickled carrot and papaya, and dipping sauce.