Spray slow cooker with cooking spray.
Place a handful of the onion slices on the bottom of the slow cooker, add in the pork chunks and top with the remaining onion slices.
5-7 lb pork roast cut into large chunks, 2 onions sliced
Sprinkle the dry rub and minced garlic over the meat and onions. Pour in enough water to mostly cover the pork, making sure the meat stays moist while cooking.
2-4 tbsp pork rub, 1/2-1 tbsp minced garlic, enough water to mostly cover the pork chunks
Put on slow cooker lid, and cook on low 8-10 hours.
Once done, the pork should shred easily; it should just fall apart. Place meat on a plate and shred, discarding of any fat.
Strain the juices that are left in the slow cooker and set aside.
Add the shredded pork back into the slow cooker and add in 1/2 c. of the reserved juices. This will help keep the meat moist and not dried out. If you want to add more juices you definitely can!
Place slow cooker on warm until ready to serve.