Place the prawns, garlic, curry paste and lime zest in a food processor and pulse until everything is chopped but still has some texture.
Sprinkle the cornflour on a large plate. Take a small tsps worth of the mixture and roll it in the flour. Heat a drizzle of olive oil in a large non stick frying pan and fry this " tester" for a couple of minutes. Check seasoning and add more salt to the rest of the mixture if needed.
Make small patties- about a heaped dessertspoon each- with the remaining mixture. Coat them in the cornflour.
Heat another tbsp oil in the frying pan over a medium heat and add the patties to the pan. Fry for 3-4 minutes on each side until golden and cooked through. Place on kitchen paper to absorb excess oil.
Serve immediately with a squeeze of lime and a drizzle of sweet chilli sauce.