Rinse and dry the pork shoulder. To do this, take the pork out of the packaging and use paper towels to soak up all the excess liquid.
Combine the rub ingredients into a small bowl. Use your hands to add the rub all over the pork.
Heat up a skillet to medium/medium-high heat. Add the olive oil. Sear the pork on each side for about 3-5 minutes until golden brown. (5 minutes on the big sides and 3 minutes on smaller sides).
While the pork is searing, prepare the sauce mixture and chop the onion and garlic.
Place the pork in the slow cooker (fat cap up).
Add sauce mixture, onion, and garlic.
Slow cook the pork on low for about 8 hours or until done. The pork should be tender enough to shred.
Remove the pork from the slow cooker and let it cool so you can trim the fat and drain some of the excess liquid (optional).
Shred using two forks.
Optional: Add extra BBQ sauce to the pork after pulling.
Store in an airtight container in the fridge.
For optimal enjoyment, serve with buns and coleslaw!