Cut the kingfish into eight 1/2cm thick, about 10cm long pieces. Place two onto a board, one behind the other and carefully insert a skewer through the centre. Repeat with remaining fish.
Finely grate the lime rind onto a plate, add the oil and a sprinkling of salt. Add the fish and turn to coat. Allow to marinate no longer than 5-10 minutes.
Preheat char-grill pan over high heat until very hot. Cook the fish two at a time for 30 seconds. Turn over and cook for 10 seconds then remove to a plate.
For the zucchini and coriander salad, combine the oil, lime rind, lime juice and salt in bottom of a bowl. Thinly slice the zucchini lengthways and add to the bowl with the coriander. Toss gently to coat then pile onto the fish to serve.