Make small slits in the pork using a paring knife, and stuff slits with garlic clove halves. Sprinkle all sides evenly with salt and pepper. Press “Sauté” on Instant Pot, and allow it to heat 2 to 3 minutes. Add oil. Place 2 pieces of pork in oil, and cook, turning occasionally, until browned on all sides. Transfer to a plate, and repeat with remaining 2 pieces of pork.
Add browned pork back to Instant Pot, and pour in water. Press “Cancel”. Place cover on Instant Pot, and turn valve to “Sealing” position. Set to “High Pressure” for 65 minutes.
Carefully release the valve, and let steam escape. Transfer pork to a plate, and shred with a fork.