Trim excess fat from the pork shoulder if desired (leaving some fat will add flavor). Cut the pork into 3-4 large chunks to promote even cooking.

Heat vegetable oil in a large skillet over medium-high heat. Brown the pork pieces on all sides, about 3-4 minutes per side.

Place chopped onions at the bottom of your slow cooker.

In a medium bowl, whisk together barbecue sauce, chicken broth, apple cider vinegar, brown sugar, Worcestershire sauce, minced garlic, smoked paprika, cumin, salt, pepper, and cayenne (if using).

Place the browned pork on top of the onions in the slow cooker. Pour the BBQ mixture over the meat, ensuring it's well coated.

Cover and cook on LOW for 8-10 hours or on HIGH for 5-6 hours, until the pork is extremely tender and falls apart easily when prodded with a fork.

Once cooked, remove the pork from the slow cooker and place it on a cutting board. Using two forks, shred the meat, discarding any large pieces of fat.

If desired, skim excess fat from the surface of the cooking liquid. For a thicker sauce, transfer the liquid to a saucepan and simmer for 10-15 minutes to reduce.

Return the shredded pork to the slow cooker and mix with the sauce. Let it sit for 10-15 minutes to absorb the flavors before serving.

Toast hamburger buns if desired. Pile the pulled pork onto the buns and top with coleslaw and pickles if using.