Add all the dry rub ingredients to a large bowl and whisk them together. (Or instead, you can use 4-5 tablespoons of a commercial pork rub mix of your choosing.)
Trim the excess fat from the pork roast and cut it into 4 similar-size chunks. Add the pork roast chunks to the rub mix and coat them well.
Place the pork chunks into the Instant Pot, spacing them out as best as possible. Pour the water and cider vinegar over them.
Secure the lid and make sure the vent is set to the sealing position. Pressure cook on high pressure for 40 minutes. Let the pressure release naturally for 5 minutes, then open the vent and let the rest of the pressure release.
Remove the pork to a large bowl and shred it with 2 forks. Add your favorite BBQ sauce as desired. Or use the juice from the Instant Pot – it’s loaded with awesome flavor!