Butterfly prawns by removing heads and cutting through the center body from belly to tail without cutting through the skin.
Heat white wine vinegar and sugar in a small saucepan over medium heat.
Add thick slices of ginger to the vinegar mixture.
Add sliced chilli and simmer for five minutes until the sauce is reduced and sticky.
Preheat a ridged grill pan and season prawns with sea salt and vegetable oil.
Grill prawns for 3 minutes per side until charred and cooked through.
Transfer the grilled prawns into the pan containing the reduced sweet and sour sauce.
Stir in chopped coriander and a squeeze of fresh lime juice.
Toss to coat the prawns thoroughly and serve immediately.