Wash the prawns.
Holding them firmly by the tails, remove the shell, leaving the tail shell intact.
Cut the prawns in half lengthways almost to the tail and remove the black intestinal vein.
Flatten the prawns.
Sprinkle them with the sherry, dip in the egg and coat in the cornflour.
Repeat the coating.
Heat the oil to 180C or until a cube of day-old bread browns in 30 seconds.
Deep-fry the prawns for 2-3 minutes.
Drain on absorbent kitchen paper and serve at once, Garnished with fresh coriander.