I always recommend using turkeys that are between 10 and 12 pounds, as they have the best flavor and texture. Rather than use a larger turkey for more guests, it’s better to cook multiple smaller birds (using different methods!). Removing the wishbone is not strictly necessary, but it makes carving easier down the line. To remove the wishbone, start by lifting the skin around the turkey’s neck opening to reveal the Y-shaped bone underneath. Use the tip of a sharp paring knife to cut into the flesh above both halves of the Y.
Cut along the bottom of each side of the Y with your knife.

Slide your finger behind the bone and start pulling it forward. The top should release pretty easily, though a little help with the tip of the paring knife might be necessary.
Pull the wishbone out. If it cracks or leaves behind bits of bone, you can grab them with a clean kitchen towel or paper towel and pull them out.

If there are any problem spots (the thigh joints in particular can sometimes be quite tough to get through with scissors), use a heavy cleaver or chef’s knife to cut through them. Save the backbone for stock or gravy.
Flip the turkey over and splay its legs outward as suggestively as you please.

Press down firmly on the breastbone until you hear and feel it crack, so that the breasts will sit flat.

You can use your favorite barbecue spice rub mixture for the turkey, or use mine: 2 tablespoons kosher salt, 1 tablespoon paprika, 1 teaspoon smoked paprika, 1/2 teaspoon ground black pepper, 1/2 teaspoon ground yellow mustard seed, 1/2 teaspoon ground coriander seed, 1/2 teaspoon ground cumin seed, 1/4 teaspoon ground cayenne pepper, 1 teaspoon granulated garlic powder, 1 teaspoon granulated onion powder, 1 teaspoon ground sage, 2 tablespoons light brown sugar, and—here’s the secret ingredient—a tablespoon of baking powder.

Rub the turkey on all surfaces with the salt and spice mixture. At this point, place the turkey on a tray, cover it loosely with plastic wrap, and let it rest at least overnight and up to 3 days in the refrigerator. This will allow time for the salt in the rub to slowly work its way into the meat, which will not only season it more deeply but also help the turkey retain more juices as it roasts. Read up on how dry-brining works for more details.

When you’re ready to cook (that’s about 3 1/2 hours before everyone is ready to eat), ignite half a chimney’s worth of charcoal and dump it out into a kettle grill.

Pile the coals along one side of the grill. The goal is to create a cooler zone on the other side so that the turkey slowly cooks via indirect heat.

Place the cooking grate over the coals, cover the grill, let it preheat for about 10 minutes, then scrub it clean with a grill brush. Place the turkey on top of the cooler side of the grill with the legs facing the coals. As leg meat can safely withstand a higher cooking temperature, the goal here is to keep the breast cooking as gently as possible so that it retains juiciness while gaining smoke flavor.

When the turkey is in place, put 4 chunks of hickory hardwood directly on top of the coals by lifting the grate (or using the hinged flap, if your grates have one).

Keep a lazy eye on the thermometer so that you don’t miss the alarm when it goes off. We’re aiming for a final temperature of 150°F here—that’s 15°F lower than the USDA’s recommended temperature of 165°F, but the turkey you get will be much juicier, and so long as it’s rested for at least 4 minutes, it will be just as safe as a turkey cooked to 165°F—but I like to set my alarm at 145°F, because the last few minutes of cooking require closer monitoring.

The inside of the grill should hover between 225°F and 275°F for optimally gentle cooking. You can control the temperature by opening and closing the vents (the more closed they are, the less oxygen the coals will get, and the cooler they’ll smolder). Add more wood chunks to the coals every half hour, and, if necessary, add more coals if the original coals start to burn out too far.

A 10- to 12-pound turkey will take around 3 hours, give or take half an hour in either direction. Once the turkey hits 145°F, continue cooking it, moving the thermometer around and taking its temperature in various locations as it approaches its final temperature of 150°F in the breasts.

Transfer the turkey to a cutting board and let it rest for 15 minutes. This will allow the internal juices to settle and thicken slightly so that they don’t run around the board as you carve.

To carve, start by removing the legs. Pull gently at the leg with one hand, and you should be able to easily slip a knife into the joint between the leg and the breast.

Both legs should come off quite easily. If the turkey is too hot for your delicate fingers, plastic gloves can help.

Use a knife to cut along the side of the thigh bone with the larger pieces of meat on it to completely remove the meat.

Slice the thigh meat into 1/2-inch slices, with the skin side up.

The meat should have a nice pink hue around its edges from the barbecue.
Remove the wings from the breasts by positioning the breast upright and holding it by one of the wings. Jiggle the wing back and forth a little to locate the joint, then cut through it with a sharp knife. Repeat with the other wing. You can remove the drumette from the flat/wing tip in the same manner that you separated the drumstick from the thigh.

Start removing the breast halves from the breastbone by running your knife down one side of the sternum.

Slice the breast meat into 1/2-inch serving slices.

Source: www.seriouseats.com