Cut the Pork Shoulder (1.7 kilogram) in half and use the Vegetable Oil (2 tablespoon) to brown on both sides in the pot, about 3 minutes per side.
Take out the pork and combine Barbecue Sauce (2 cup) and Water (1/2 cup) in the pot, bringing it to a boil.
Add pork, seal the pressure cooker, and set to high pressure cooking for 75 minutes at low heat after pressure has been reached.
Allow the pressure cooker to depressurize naturally, about 15 to 20 minutes. Once the pressure valve has dropped, remove the lid carefully. Take out pork and set aside.
Strain the juices from the pot, resrving 1/2 cup. Rip apart the pork using forks.
Stir the remaining cup of BBQ sauce and reserved 1/2 cup juices to the pot, and mix while bringing to a boil. Add pulled pork and stir well.
Simmer for a few minutes.
Put on a crusty roll or French baguette as an open faced sandwich, or panini or other bread for a regular sandwich, adding more BBQ sauce if desired. Or, use as a topping on hot rice.