Preheat your smoker to 225°F (107°C) using high-quality wood pellets like hickory or applewood.
Remove the thin membrane (silver skin) from the back of the ribs using a paper towel for better grip.
Apply a thin layer of yellow mustard over the entire surface of the ribs to act as a binder for the spices.
In a small bowl, combine the sea salt, black pepper, smoked paprika, and garlic powder, then sprinkle evenly over both sides of the ribs.
Place the ribs on the smoker grate, bone-side down, and smoke for approximately 3 to 4 hours or until the meat has pulled back from the bones.
While the ribs smoke, trim and halve the Brussels sprouts, then toss them with olive oil and a pinch of salt.
During the last 30 minutes of smoking, place the Brussels sprouts on a baking sheet in a 400°F oven and roast until charred and tender.
Brush the sugar-free BBQ sauce onto the ribs during the final 15 minutes of smoking to allow the glaze to set.
Remove the ribs from the smoker, let them rest for 10 minutes, then slice and serve alongside the roasted Brussels sprouts.