For rub, in a small bowl combine pepper, paprika, and garlic salt. Trim fat from ribs. Place ribs in a shallow dish. Sprinkle rub evenly over ribs; rub in with your fingers. Cover and chill for 1 to 4 hours.
At least 1 hour before smoke cooking, soak wood chunks in enough water to cover. Drain before using.
In a smoker arrange preheated coals, drained wood chunks, and water pan according to manufacturers directions. Pour water into pan. Place ribs, bone sides down, on grill rack over water pan. Cover and smoke for 2 to 2-1/2 hours or until tender. Add additional coals and water as needed to maintain temperature and moisture.
Meanwhile, for sauce, in a small saucepan whisk together mustard, bourbon, molasses, soy sauce, and brown sugar. Cook and stir until mixture comes to boiling; reduce heat. Simmer, uncovered, about 10 minutes or until desired consistency.
Just before serving, brush ribs with some of the sauce. Pass remaining sauce with the ribs. Makes 4 servings.