Given the inevitable variation in burger thickness and barbecue temperature, not to mention personal taste, it’s hard to give precise guidelines for cooking times and turning points. But I can say that, stuck or not, I like to flip my burger after just 3-4 minutes, as I want it fairly rare. And a couple of minutes on the other side usually finish it off. My wife, who likes her burger literally raw (and I mean fridge cold) in the middle, gives it scarcely a minute on each side, but the barbecue has to be very hot, Don’t forget to season lightly with salt and pepper just before you turn the burger.