1. Mix all spicy chili rub ingredients in small bowl, set aside.
2. If using a fresh ham or picnic roast, remove skin (see illustration below). Massage dry rub into meat. Wrap tightly in double layer of plastic wrap; refrigerate for at least 3 hours. (For strong flavor, the roast can be refrigerated for up to 3 days.)
3. At least 1 hour prior to cooking, remove roast from refrigerator, unwrap, and let it come to room temperature. Soak 4 (3-inch) wood chunks in cold water to cover for 1 hour and drain. Meanwhile, light a large chimney starter filled a bit less than halfway with charcoal briquettes (about 2 1/2 quarts, or about 40 briquettes), and burn until all the charcoal is covered with a layer of fine gray ash.
4. Empty the coals into the grill; build a modified two-level fire by spreading the coals onto one side of the grill, piling them up in a mound 2 or 3 briquettes high, leaving the other half with no coals. Open the bottom vents completely. Place the soaked wood chunks on the coals. Position the cooking grate over the coals, cover the grill, and heat until hot, about 5 minutes (you can hold your hand 5 inches above the coals for 2 seconds). Use a grill brush to scrape the cooking grate clean.
5. Set unwrapped roast in disposable pan (see illustration below) and place it on grate opposite the fire, (see illustrations below). Open grill lid vents three-quarters of the way and cover, turning lid so that vents are opposite chunks to draw smoke through the grill. Cook, adding about 8 briquettes every hour or so to maintain an average temperature of 275 degrees, for 3 hours.
6. Adjust oven rack to middle position and preheat oven to 325 degrees. Place roast in pan and wrap with heavy-duty foil to cover completely. Place pan in oven and cook until meat is fork-tender, about 2 hours.
7. Slide the foil-wrapped pan with the roast into a brown paper bag. Crimp top shut; rest roast 1 hour. Transfer roast to cutting board and unwrap. When cool enough to handle, "pull" pork by separating roast into muscle sections (see illustration, below), removing fat, if desired, and tearing meat into thin shreds with fingers. Place shredded meat in large bowl ; toss with 1 cup barbecue sauce, adding more to taste. Serve with remaining sauce passed separately.
STEP BY STEP: Key Steps to Pulled Pork
1. If using a fresh ham or pinic roast, cut through the skin with the tip of a chef's knife. Slide the blade just under the skin and work around to loosen it while pulling it off with your other hand. Boston butt, or shoulder roast, does not need to be trimmed.
2. Set the unwrapped roast, which has been placed in a disposable aluminum pan barely larger than the meat itself, on the cooking grate opposite the coals and the wood.
3. After cooking, as soon as the meat is cool enough to handle, remove the meat from the bones and separate the major muscle sections with your hands.
4. Remove as much fat as desired and tear the meat into thin shreds.
STEP BY STEP: Using a Charcoal Grill for Indirect Cooking
1. Pile the coals on one half of the grill and leave the other half free of coals.
2. Place soaked and drained wood chunks or a foil packet filled with wood chips on top of the coals. Set the top grate in position, heat briefly, and then scrape the grate clean with a grill brush. You are now ready to cook over the cooler part of the fire. Put the food on the grill and set the lid in place. Open the air vents as directed in individual recipes.
3. A grill thermometer inserted through the vents on the lid can tell you if the fire is too hot or if the fire is getting too cool and you need to add more charcoal. You will get different readings depending on where the lid vents are and thus where the thermometer is in relation to the coals. Because you want to know where the food is being cooked, rotate the lid so that the thermometer is close to the food. Make sure, however, that the thermometer stem does not touch the food.