Combine the chillies, lime zest, lime juice, garlic, coriander, coconut, olive oil and soy sauce in a food processor; blend until smooth. Place the prawns in a large bowl. Pour the sauce over the prawns and toss to coat. Cover and allow to marinate at least 2 hours.
Preheat the barbecue for medium-high heat and lightly oil the grate.
Thread the prawns onto skewers, piercing each prawns near the head and tail.
Cook the skewers on the barbecue, turning frequently until nicely browned on all sides and the meat is no longer pink in the centre, 2 to 3 minutes per side.