Combine prawns, lime juice, garlic, chilli and olive oil in a medium bowl. Set aside for 10 minutes to marinate.
Meanwhile, cook quinoa according to packet instructions, keep warm.
Combine quinoa, corn, kidney beans, avocado, capsicum, and coriander leaves, on serving platter. Preheat a barbecue or chargrill on medium-high, cook prawns, turning for 3 minutes or until cooked through, arrange on salad; serve.