The most important part of cooking a duck is to get rid of that fat. There are several strategies for doing this like steaming the duck over boiling water for about 20 to 30 minutes. This is a traditional method, but it cooks the duck and blocks the absorption of smoke flavor when you cook it. Another trick is to pierce the skin of the duck at regular intervals, about every one inch over the entire surface of the duck, but be careful. You want to cut through the skin and fat but you don't want to cut into the meat. This can best be done by very gently pushing into the skin with a knife. The fat is easier to cut than the meat so once you are through the skin push carefully until you feel resistance. These vents will allow the fat to drain from the duck.
Now you want to slow roast your duck. You can do this in two ways, with a grill or with a smoker. Let's take the grill first. The old traditional way of cooking duck was always over a live fire, particularly on a rotisserie. This let the fat drain away and burn off in the fire. Now with a gas grill that grease is just going to catch fire and you will end up getting that bird nice and crispy in about 10 minutes. Not way we want. Whether you are using a gas grill or a charcoal grill you want to have a drip pan that will catch the greasy fat as it drips off. If you are using a rotisserie then this is a pretty standard set up. If you are not using a rotisserie then you want to set up a drip pan that will keep the duck from touching the drippings. You also want to set the duck so that it can effectively drain off that fat. One great trick is to use a standing chicken roaster like those that are used in beer can chicken. You don’t want the can, just the cage that holds it. This is a great position for the duck to be in while it roasts.
On a grill you want to get a roasting temperature around 325 degrees F. and hold it there for about 2 to 3 hours. Yes, you will cook duck more than you would chicken. Remember, I said they were different. This longer time will allow that fat to melt away. Of course you are grilling indirectly since you are using a drip pan. Never put a fire under a drip pan. That just makes bad smoke. There are a couple of things to look out for so you will know when your duck is done. First of all the internal temperature needs to hit 165 degrees F. You probably won't have to worry too much about this, but you should check anyway. Next you want to make sure that the skin is thin and crisp. The fat of a duck sticks to the skin so you know it is gone when the skin is nice and crispy. And lastly, the duck should have a nice brown, even color over the surface.
Now for the smoking. You will want to rig up your duck just like you would on the grill without a rotisserie. You want a drip pan, but don’t want the duck sitting in the pan and you want the duck standing up so that the fat can drain more easily. Now you want to smoke your duck at about 225 to 250 degrees F. This is a good temperature for poultry. You will want to smoke for about 4 to 6 hours, depending on the temperature you are holding. For the smoke you want to go for a good fruit wood like apple or cherry or perhaps hickory. Oak might be a little mild and mesquite will probably be too strong. You want a good supply of smoke. Remember that duck has plenty of flavor so you can add a lot to it without overpowering the duck.
Now while you will be able to get that fat out of the duck on the smoker you might not get the crispy skin you want. This is because the temperature might not be high enough to achieve it. You can transfer the smoked duck to a grill for a few minutes. Set the grill up for indirect grilling, but have a hot fire. Make sure to turn the duck so that every side gets the intense heat and keep an eye on it so it doesn’t start to burn. You can also put the duck in your oven for about 15 minutes at 500 degrees. This will get it crispy.
Okay, so that’s the basics of preparing a duck. Just a couple of other things and you should be ready to go. Duck has heavier bones than chicken so while the duck you buy might be a little heavier than a normal chicken you will end up with less meat. Plan on one duck feeding about four people provided that you have some good side dishes to go with it. Also, duck takes to sweet and fruity flavors very well. Try flavoring your duck with orange juice, apple cider, citrus rind, or berries. Also try some whole cloves, ginger and Asian spices.