Season the roast with salt (and pepper if you've successfully reintroduced it or are not on AIP). Add the roast to the Instant Pot and then add 1 cup of water, chicken stock, or beef stock, to the Instant Pot. Cook on HIGH for 70-90 minutes and let naturally release for 10 minutes before releasing the rest of the pressure. When the cooking time is up, remove the beef and shred.