1: Place the ribs on a rimmed baking sheet and season liberally on both sides with salt and pepper. Refrigerate for 12 hours, up to 24. (Do not go longer than 48 hours.)
2: Prepare the rub: Combine all the rub ingredients in a small bowl and set aside.
3: Make the sauce: Melt the butter in a cast iron skillet or other pan. Saute the onions over medium-high heat until translucent, 5 to 8 minutes. Deglaze the pan with the beer and let reduce slightly. Stir in the brown sugar, salt and pepper to taste, and the prepared barbecue sauce. Let the sauce simmer for several minutes so the flavors blend. Set aside.
4: Season the ribs with the rub.
5: Heat the grill or smoker to 250 degrees and add wood chunks or hardwood chips to the coals. Arrange the ribs on the grill grate and smoke for 3 1/2 to 4 hours, or until tender and the meat has pulled away from the bones by 1/2 to 1 inch.
6: Brush the ribs with the barbecue sauce and continue to cook them for 15 to 20 minutes to let the sauce set up. Serve the ribs immediately with more sauce on the side.
