Trimming Your Ribs: I suppose I'm the best guy to talk about ribs, though I should mention that I'm doing this under serious protest. St. Louis-style ribs are pork spareribs that have been trimmed of the rib tips and skirt to create a uniform rectangular shape. If you can't find St. Louis-style ribs in your market, ask your butcher to trim spareribs for you or prepare them yourself at home. To prepare St. Louis-style ribs, place the spareribs bone-side up on a cutting board. Usually, there will be a flap of meat that runs along the slab, called the skirt. Remove the skirt; it can be cooked separately, and it's a very flavorful part of us pigs. Remove the excess fat. Cut along the end of the rib bones, cutting between the bone and cartilage, to remove the irregular-shaped portion of meat attached to the ribs. Remove the tough outer membrane. Slide a butter knife under the membrane and pry it up, then grab a hold of it with a clean paper towel and peel it off. Last, remove the rib tips (they can be cooked separately) and the opposite end to square up the rack.