Mix the coconut and the panko together with about half of the lime zest. Put in a bowl.
Mix the egg with the water and salt in a second bowl
Put the flour in the third bowl.
Make a little production line in this order: raw prawns, bowl of flour, bowl of egg, bowl of coconut-panko mixture and lastly a big plate.
Take the prawns piece by piece by their tails and first drag them through the flour, then through the egg and last through the panko mixture. Put them on a plate
Heat the oil in a wok or deep frying pan and fry the prawns until golden and brown.
Make sure you don't put too many prawns in the pan (it will cool of too much and the fat will get into the coconut mix)
Take the prawns out of the oil and leave them to drain on kitchen paper.
Sprinkle the rest of the lime zest over them and serve with chili sauce. A mix of mayonnaise with a bit of chipotle sauce will also be delicious