Turn the slab to the bone side. On center-cut and spareribs there is a flap of thick meat from the diaphragm that most chefs remove. I slice it off, toss it in the smoker, and munch on it a few hours into cooking. Cook’s bonus!
If the butcher has not removed the shiny silvery membrane on the concave bone side, you should do so. It can get rubbery. In addition, removing it helps the layer of fat under the membrane melt and drain.
Insert a butter knife or, as this cook is doing, an ice pick, between the membrane and the meat at one end. Work your fingers around under it to loosen it, so you can get a grip on it. Gently begin peeling it off, trying not to rip it. I like to use a paper towel to help me grip the slippery thing.
If the slab is irregular at the ends or too long to fit on the smoker, trim off a bone or two. Cook these loose bones with the slab. They’ll be done in a couple of hours, so you can grab them before the rest of the ribs are done. Another cook’s bonus!