Remove the pork from the slow cooker, place it on a cutting board. Meanwhile, stir in 1 tablespoon of cornstarch to the sauce in the slow cooker, put the lid on and turn the heat to high. Let it heat for about 15 minutes. With 2 forks (or with clean hands), shred the meat, discarding any fat or bones. Add the shredded meat back to the sauce in the slow cooker. Divide the meat evenly among the sandwich buns, topping with cole slaw, if desired.