In a large mixing bowl, add the dark beer, soy sauce, Worcestershire sauce, brown sugar, hot sauce, garlic salt, black pepper, 2 tsp of Pit Boss Sweet Heat Rub, and quick curing salt. Whisk well to combine everything, or until the brown sugar is dissolved. Pour the marinade into a large resealable plastic bag or large mixing bowl and set aside.
Using a sharp knife, trim any fat or connective tissue off the flank steak. Slice the beef into ¼ inch thick slices against the grain (this is easiest if the meat is partially frozen).
Place the beef slices into the resealable plastic bag, seal and massage the marinade into the meat. Allow the meat to marinade in the refrigerator for 24 hours.
When you are ready to smoke your jerky, remove the beef from the marinade and discard the marinade.
Fire up your Pit Boss Smoker and set the temperature to 200°F. If using a sawdust or charcoal smoker, set it up for medium low heat.
Arrange the meat in a single layer directly on the smoker grate. Smoke the beef for 4-5 hours, or until the jerky is dry but still chewy and still bends somewhat.
Remove the jerky from the grill with tongs and transfer to a resealable plastic bag while still warm. Let the jerky rest for 1 hour at room temperature.
Squeeze any air out of the resealable plastic bag and refrigerate the jerky. It will keep for several weeks.