Thread the prawns lengthways onto 16 small bamboo skewers (soak the skewers in water for 30 minutes beforehand, so that they won't burn).
Combine the coriander, 1/3 cup (80ml) of the lime juice, the green chilli, sesame oil, cumin seeds and garlic in a small bowl. Brush the marinade thoroughly over the prawns and put aside for 10 minutes.
Meanwhile, combine the mangoes, spring onions, red chillies, brown sugar, mint leaves, snow pea sprouts and the remaining lime juice in a medium serving bowl.
Preheat a barbecue or a ridged, iron grill pan. Cook the prawns for 1 minute on each side or until cooked through. Serve with bowls of the salad.