I don`t have a Weber Q, but I do have a hooded 4 burner BBQ, that I put those coal briquettes dodads in on top of the volcanic rocks. I turn the gas on for a few minutes to light them up and then bung in a roast lamb, pork or a couple of chooks on the spit roast turner and place an aluminium foil tray full of veges underneath the cooking meat to catch the dripping fat to help cook the veges. Turns out well with fresh Rosemary, Sage, Salt and Pepper. The best way to cook a roast I reckon.