In a small bowl whisk together lime juice, olive oil, garlic, chili powder, cumin, paprika, salt, pepper, redpepper flakes. Pour into a resealable bag andadd shrimp. Toss to coat and marinate for 30 minutes.
Place the prawns on skewers and place on the coals. Grill on each side for about two minutes or until no longer pink.
To make the creamy avocado coriander dip, add the avocado, Greek yogurt, garlic, lime and cilantro. Pulsein a food processor until smooth.
Add salt and pepper to taste. Serve immediately with prawns.