Squeeze out any excess juice from the grated courgette, then combine it with the carrot, chicken mince, breadcrumbs, sweetcorn and egg in a bowl. Wet your hands and shape into six burgers.
Heat the oil in a large frying pan over a medium heat. Cook the burgers for 5 minutes each side, until cooked through.
Assemble the cooked burgers in the rolls with the tomatoes, cucumber, lettuce and tomato ketchup.