1. Peel off the middle part of the prawn shell leaving the head and tail on and remove the digestive track.
2. Put all the ingredients for the marinade in the bowl. Add the prawns and mix well to coat the prawns. Set aside until ready to cook.
3. Mix 50g cornflour, self raising flour, salt and water into a batter.
4. Put the remaining 50g cornflour and crushed prawn crackers onto two separate plates.
5. Heat the oil in a wok or a deep fat fryer to 170°C.
6. First dip each prawn separately in the cornflour, followed by the batter and then the crushed prawn crackers. Carefully place into the fryer, cooking the prawns for 2-3 minutes until the prawn crackers puff up and are nice and crispy.
For the Chips:
1. Julienne one large potato and soak in cold water.
2. Heat a wok or fryer to 140°C. Put the chips into the oil and cook for 2-3 minutes. This can be done well in advance.
3. Remove and allow to cool on kitchen paper.
4. When you're ready to serve, reheat the oil to 180°C and put the chips into the fryer and fry until crispy.
For the Mint and Basil Mayonnaise:
Combine all the ingredients into a bowl and mix well. Serve with the prawns and chips.