Preheat your smoker, grill, or oven to low heat, around 225°F to 250°F for smoking or 300°F for oven baking.
Remove the membrane from the back of the beef back ribs.
Pat the ribs dry with paper towels.
Rub the ribs lightly with yellow mustard or olive oil.
In a small bowl, mix the salt, black pepper, smoked paprika, garlic powder, onion powder, brown sugar, chili powder, cumin, and cayenne pepper.
Coat the beef back ribs evenly with the dry rub on all sides.
Place the ribs in the smoker, grill over indirect heat, or in a covered baking dish in the oven.
Cook low and slow until the ribs are tender and the internal temperature reaches about 190°F to 205°F.
If desired, brush with barbecue sauce during the last 20 to 30 minutes of cooking.
Remove the beef back ribs from the heat, let them rest for 10 minutes, then slice and serve.