1. Cut off the silverskin and top fat from the pork roast, and blot the excess moisture with paper towels. Then, combine the pepper and salt, and rub them liberally on the meat.
2. Program the pressure cooker to SAUTE and add the oil, then once it grows hot, brown the roast on its top and bottom, and set it aside.
3. Pour the water into the pressure cooker and scrape the browned bits from its bottom with a wooden spoon. Then, place the pork roast in the water, close the lid, and seal the valve.
4. Program the pressure cooker to 45 minutes, after which you allow another 10 minutes for the pressure to naturally release. Then, vent the valve to release any remaining pressure, remove the lid, and rest the pork roast while you make the gravy.
5. Whisk the cornstarch and water to make a slurry, then skim the excess oil layer from the broth. Program the pressure cooker to SAUTE mode and let the broth reach a boil. Add the slurry and stir, whisking until it thickens.
6. Serve the pork roast in slices, topped with the gravy and any side dish of your choice.

This video is also available for more help.