Mix together 1 Tbsp Colman's dry mustard, 1 tsp black pepper, 1 Tbsp kosher salt, 3 Tbsp paprika, 1 Tbsp garlic powder, 1 Tbsp Cumin, and 2 Tbsp of brown sugar. Mix thoroughly. This is the dry rub.
Place rub in empty spice container to allow easy application. If not just use a spoon to distribute rub on ribs.
Mix the remaining cider vinegar, brown sugar, prepared yellow mustard, Colman's dry mustard, and salt in glass bowl with a whisk to make mustard bbq sauce. Stir well to thoroughly incorporate all the ingredients.
If you have one, place sauce in a squeeze bottle. If not just baste the sauce on.
Prepare your smoker of choice for the ribs.
Apply dry rub to ribs. 1-2 Tbsp of dry rub per side is perfect. Make sure to get the rub all over the ribs. Use surgical gloves if you have them to really get the rub well incorporated into the ribs. Otherwise a nice sprinkle and pat with the hands is sufficient.
Place ribs in smoker and get them going. My smoker takes roughly 3.5 hours for perfect baby back ribs, but follow the directions on the type of smoker you have. I like to remove the ribs from the heat when the meat pulls back ¼" from the bone. This is a good way to check for doneness without an instant read thermometer. If you do have an instant read 190f is a perfect temperature for tender smoked ribs.
During the last 15-20 minutes of smoking remove the ribs and apply the Carolina mustard bbq sauce to the ribs with a baster. Return the ribs to the heat for 20 more minutes of smoking.
After the final 20 minutes, remove the ribs and cut them up. I like to slather some more of the sauce on and serve it on the side as well. Enjoy!