Remove the membrane from the bone side of the rack by sliding a knife under one edge and pulling it away with a paper towel. Trim excess hard fat to about a quarter-inch, then pat the entire rack dry with paper towels.
Rub a thin layer of yellow mustard or hot sauce over all surfaces of the ribs as a binder. Combine the kosher salt, black pepper, and garlic powder, then coat the entire rack generously on all sides, pressing the rub firmly into the meat.
Place the seasoned ribs uncovered on a rimmed baking sheet and refrigerate for at least 1-2 hours, or ideally overnight up to 24 hours, to allow the salt to deeply penetrate the meat.
Fire up your smoker 45-60 minutes before cooking and bring it to a steady 250-275°F set up for indirect heat. Add your wood chunks or chips and ensure the smoke is thin and blue, not thick and white, before placing the meat on.
Place the ribs bone-side down on the smoker grate and insert a leave-in probe thermometer into the thickest part of the meat. Smoke at 250-275°F undisturbed for 4-5 hours until a deep mahogany bark forms and the internal temperature reaches approximately 165-170°F.
Once the bark is fully set and the internal temperature hits 165-170°F, transfer the ribs to a sheet of heavy-duty foil or pink butcher paper. Optionally add butter and beef broth, then wrap tightly and return to the smoker bone-side down.
Continue smoking the wrapped ribs at 250-275°F for another 2-3 hours until the internal temperature reaches 200-205°F and the probe slides into the meat with no resistance, like passing through softened butter.
Remove the ribs from the smoker while still wrapped and place them in a dry cooler lined with towels or an oven set to its lowest setting. Rest for a minimum of 45 minutes, up to 2 hours, for maximum juiciness.
Carefully unwrap the rested ribs, transfer them bone-side down to a cutting board, and slice between the bones into individual ribs with a sharp knife. Serve immediately with your favorite sides.