Heat: Whether using a charcoal or gas grill, the secret is in perfecting the roasting temperature. Now I would love to tell you just how many coals to light or the right setting for your burners, but I can't. That depends on your grill. You want a low heat, meaning you can hold your hand where the roast will be sitting for the count of three and no less. You'll want it a little cooler if you keep the lid down the whole time. Keep the temperature low, unless you're planning to get the surface of the meat seared, forming a delectable crust. If so, start out on a high temperature for about 15 minutes and then reduce it. If you’re using charcoal, bank the coals close to the meat for about 15 minutes then pull them back, away from the roast.
Threading: Now the hardest part about putting a whole roast on a rotisserie is getting the spit through the meat. The first step is taking a good look at your roast. You'll want it as evenly balanced on the spit as you can get it. Skewer the roast lengthwise through the longest part of the meat while still getting it as centered as possible. Once you know where the spit will enter and exit the roast, take something long and sharp to make a hole from each end. A fillet knife works well for this task. Next, drive the spit through the roast and clamp it down tight with the forks. Make sure the meat is firmly secured.
Seasoning: You can season the roast however you want. A good dry rub works best. Since the turning action of a rotisserie helps hold in moisture you don't need to worry about marinating or basting, though you can if you wish. I like to keep seasonings simple because it lets the flavor of the meat stand out more. A simple sprinkling of salt and pepper works great.
Gravy: Lastly, use a drip pan to catch the flavor of the meat as it cooks. Not only does this keep your grill clean but gives you the makings for nice gravy. To keep the drippings from drying out and burning add water to the drip pan. You will need to keep an eye on it so that the water doesn't all boil away. If you time it right you'll have perfect gravy without added effort. The drippings from the meat combined with the seasonings of your rub, slowly roasted together are truly fantastic.
Carving Once you have the roast off the rotisserie, cover loosely with foil and let it rest for about 10 minutes. Now you are ready to carve. I prefer very thin slices piled high. It makes for a great presentation and keeps the meat tender. Once you've tried a rotisserie roast you won't want to cook one in the oven again.