Step 1: Prepare the herb paste: Place the herbs, garlic, salt, sugar, paprika, pepper, hot red pepper flakes, and mace in a food processor and finely chop. Work in enough oil to obtain a thick paste.
Step 2: Spread the herb paste all over the pork shoulder using a rubber spatula. You can cook the shoulder right away, but it will have even more flavor if you let it marinate in the refrigerator for 4 to 6 hours, or even overnight.
Step 3: Set up your smoker following the manufacturer’s instructions and preheat to 225 degrees. Add the wood as specified by the manufacturer.
Step 4: Place the pork in the smoker and smoke until crusty and dark brown on the outside and cooked through (the internal temperature will be 195 degrees), 6 to 8 hours, depending on the size of the shoulder.
Step 5: Transfer the pork shoulder to a cutting board and let cool for 15 minutes. Remove the skin, bones, and gobbets of fat from the shoulder and pull the pork into meaty shreds with your fingers. You may want to wear heavy rubber gloves for pulling. Alternatively, chop the meat with a cleaver. Serve on buns, if desired. Serve with the Mustard Barbecue Sauce.