In a small bowl, combine the smoked paprika, garlic powder, onion powder, cumin, black pepper, kosher salt, chili powder, brown sugar, and cayenne (if using). Mix until well combined.

Pat the pork shoulder completely dry with paper towels. This helps the rub adhere and promotes better browning.

Rub the spice mixture all over the pork shoulder, pressing firmly so it adheres on all sides. For best results, do this the night before and refrigerate the seasoned pork uncovered overnight.

Heat 1 tablespoon of olive oil in a large cast-iron skillet or heavy-bottomed pan over medium-high heat until shimmering and just starting to smoke.

Sear the pork shoulder for 3–4 minutes per side until a deep golden-brown crust forms on all sides. Don't rush this step — good caramelization equals deeper flavor.

Transfer the seared pork to your slow cooker insert.

Scatter the sliced onion and smashed garlic cloves in the bottom of the slow cooker around and under the pork shoulder.

In a small bowl or measuring cup, whisk together the apple cider vinegar, chicken broth, and Worcestershire sauce. Pour the liquid around (not over) the pork so you don't wash off the rub.

Place the lid on the slow cooker and cook on LOW for 8–10 hours, or until the pork is completely fork-tender and falling off the bone. Do not cook on HIGH if you can avoid it — the lower, longer cook produces significantly better texture.

Carefully transfer the cooked pork shoulder to a large cutting board or rimmed baking sheet. It will be very tender and may fall apart as you move it — that's exactly what you want.

Using two forks (or clean hands once cool enough), shred the pork, discarding any large pieces of fat or the bone. The meat should fall apart with almost no effort.

Skim the excess fat off the top of the cooking liquid remaining in the slow cooker. Pour the liquid into a small saucepan and bring to a medium-high boil. Reduce for 5–8 minutes until it thickens slightly into a concentrated sauce.

Pour the reduced cooking liquid back over the shredded pork and toss to coat. Taste and adjust seasoning with salt and pepper as needed. Add BBQ sauce if desired and toss again.

Serve the pulled pork on toasted buns with coleslaw and pickles for classic sandwiches, over rice or roasted vegetables for a nourishing bowl, or loaded onto tortilla chips for pulled pork nachos.

Leftovers keep in an airtight container in the refrigerator for up to 4 days, or freeze for up to 3 months.