Coat entire surface of short ribs with mustard. Season evenly with salt and pepper, making sure to fully coat the sides, top and bottom of the short ribs. Place on sheet pan fitted with wire rack and refrigerate overnight, uncovered and away from ready-to-eat food.

Preheat smoker to 275°F. Smoke until short ribs internal temperature reaches 165°F (4 to 5 hours). Wrap tightly in 2 layers of foil or peach barbecue paper and return to smoker until internal temperature reaches 205°F (1 to 2 hours). Alternatively, wrapped short ribs can be placed in a preheated 275°F oven to finish.

Rest ribs with foil slightly opened to allow the majority of steam to escape. Pour liquid into a container, skim excess fat from top. Slice between ribs into individual, meaty smoked short ribs. Alternatively, slice meat off the bone working horizontally, then thinly slice meat against the grain in 1/2-inch slices.