Preheat the barbecue for direct cooking.
While the barbecue is preheating, mix the sour cream, mayonnaise and coriander in a bowl, and season with salt and pepper.
Rub the corn cobs with olive oil, salt and pepper.
Once the barbecue is preheated, turn all burners to medium.
Place the corn cobs directly on the grill.
Close the lid and grill the corn for 3 minutes. Open the lid and turn the cobs one quarter.
Repeat this process, turning the corn every 3 minutes, until the corn has been grilled on all four sides (a total of 12 minutes).
Once the corn is cooked remove from the grill.
While the corn is still hot, coat with the coriander cream sauce on all sides.
Squeeze fresh lime juice on the corn cobs and sprinkle with the parmesan.
Just before serving, give the corn a light dusting with the paprika and cayenne pepper to taste.