Ask the experts: Cooking prawns

Q: "I've tried to cook prawns on the barbecue before, but they were overcooked and a bit tough. How long do prawns take to cook and how can you tell when they are done?"

A: Niki Bezzant, editor of Healthy Food Guide, responds:

"Raw prawns cook very quickly on a hot barbecue grill, so it is easy to overcook them when you first try.

Make sure you don't walk away from the barbecue. Stay and watch them the whole time. When they turn from grey and floppy to bright pink and firm, they're ready."