Trim the beef belly. Remove all but 1/4 inch of the fat cap. Flip the belly over and slice off the silver skin with a sharp paring knife.
In a small mixing bowl, whisk together the pepper, sugar, onion powder, salt, garlic powder, paprika, chili powder, and cayenne.
Pat the spice mixture into the meat with your hands. Make sure the entire belly is coated.
Set the beef aside to come to room temperature, approximately 35 minutes.
Set up your smoker with wood chips or pellets. If not using a pellet grill smoker, fill the water bowl halfway with water or a combination of water and apple juice. Preheat the smoker to 250°F, following the manufacturer’s instructions.
Place the beef on a rack inside your preheated smoker.
Cook for 4 hours or until the internal temperature reaches 180°F when checked with a digital meat thermometer.
Remove the beef from the smoker and wrap it in 2 layers of aluminum foil.
Place it back in the smoker and cook for another 1 to 2 hours until the internal temperature reaches 195°F.
Remove the wrapped belly from the smoker to a cutting board and allow it to rest for 20 to 30 minutes.
Unwrap the beef and place it back on the board.
Using a sharp carving knife, slice the meat thinly against the grain and serve on Kaiser rolls with BBQ sauce.