Mix tomato paste, vinegar, onion flakes, yellow mustard, molasses, garlic, olive oil, and liquid smoke in a bowl to create a thick paste. Stir brown sugar, kosher salt, cumin, chipotle pepper, paprika, black pepper, garlic powder, mustard powder, and cayenne pepper into tomato paste mixture.
Place pork shoulder into a slow cooker and add paste mixture.
Cook on High for 4 hours. Shred pork with 2 forks and remove bone. Reduce heat to Low and continue cooking for 1 to 2 more hours.
