Combine the lime dipping sauce ingredients in a bowl and stir until the salt has dissolved. Set aside.
In a mixing bowl, whisk the flour with 185ml water to form a smooth batter.
Add the prawn meat and mix again. Heat 80ml of vegetable oil in a large frying pan over a medium heat. In a wok, also heat enough vegetable oil for deep-frying to 180˚C (350˚F), or until a cube of bread dropped in the oil browns in 15 seconds.
For each prawn cake, add 2 tablespoons of the prawn mixture to the frying pan; as soon as the mixture hits the pan, flatten each cake, using the spoon or a spatula, to about 2.5mm.
Fry for 1 minute, then transfer to the wok and deep-fry for 5 minutes on each side. Drain on paper towels.
Serve warm, with the lime dipping sauce.