2 medium yellow onions, thinly sliced
4 medium garlic cloves, thinly sliced
1 cup chicken stock or low-sodium chicken broth
1 T. packed dark brown sugar
1 T. chili powder
1 T. kosher salt, plus more as needed
1/2 Tsp. ground cumin
1/4 Tsp. ground cinnamon
1 (4-1/2 to 5-pound) boneless or bone-in pork shoulder (also known as pork butt), twine or netting removed
2 Cups barbecue sauce (optional)
Place onions and garlic in even layer in slow cooker and pour in stock or broth.
Combine sugar, chili powder, measured salt, cumin and cinnamon mix in small bowl. Pat the pork dry with paper towel. Rub the spice mixture all over the pork and place the meat on top of the onions and garlic.
Cover and cook until the pork is fork tender, about 6 to 8 hours on high or 8 to 10 hours on low.
Turn the slow cooker off and remove the pork to a cutting board. Set a fine-mesh strainer over a medium heatproof bowl. Pour the onion mixture from the slow cooker through the strainer and return the solids to the slow cooker. Set the strained liquid aside.
If the pork has a bone, remove and discard it. Using 2 forks, shred the meat into bite-sized pieces, discarding any large pieces of fat. Return shredded meat to the slow cooker, add the barbecue sauce, if using, and mix to combine. If you’re not using barbecue sauce, use a spoon to skim and discard the fat from the surface of the strained cooking liquid, and then add 1/4 of the liquid at a time to the slow cooker until the meat is moistened. Taste and season with salt as needed.