You can usually find boneless pork shoulder at the butcher counter of Chinese or Asian supermarkets. If you go to a regular grocery store, they likely sell boneless pork shoulder in large pieces that are between 3 to 4 pounds. Use half of it for this recipe and save the rest for something else, like slow cooker pork. If you can only find bone-in pork shoulder or pork butt, you'll need 2 to 2 1/2 pounds.