In a food processor, blend together the prawns, spring onions, carrots, kohlrabi, galangal, mint, basil and chilli to a coarse texture, rather than a completely smooth paste. Use a tablespoon to scoop walnut-sized balls out of the mixture and coat each ball in the rice flour.
Heat the vegetable oil in a deep heavy-bottomed pan or wok, until a breadcrumb sizzles and browns when dropped in it. (CAUTION: hot oil can be dangerous - do not leave unattended.)
Add each fritter to the pan, one-by-one, until the mixture is used up (you may have to cook the fritters in batches if necessary).
When the fritters are golden-brown, remove from the pan with a slotted spoon and transfer to a dish lined with kitchen paper.
Serve straightaway.