Mix the turkey mince, 2 tbsp sweet chilli sauce, soy sauce, ginger, garlic, lime rind, spring onions, half the coriander and plenty of freshly ground black pepper until well combined. Form into four burgers (the mixture will be quite wet, although this will result in moist, juicy burgers).
Preheat the grill to hot. Arrange the burgers on a foil lined grill pan and grill for 6-7 minutes on each side until golden.
Grill the burger buns until toasted. Arrange a burger on each toasted bun base, top with lettuce and tomato if liked. Mix the remaining coriander with the mayonnaise and season with freshly ground black pepper. Top with a spoonful of mayonnaise and a drizzle of remaining sweet chilli sauce.