Remove the center stems from the greens. Discard the stems and coarsely chop the leaves. Set aside.
Chop the salt pork into bite-sized pieces.
Select the SAUTE function on the Instant Pot.
Add the salt pork and cook for 3-5 minutes to render off some of the grease, but do not drain the grease.
Add the water to the Instant Pot and scrape up any bits of salt pork that have stuck to the bottom of the pot. Bring the water to a boil and simmer the salt pork for five minutes.
Add the cider vinegar, sugar, salt, and pepper to the pot. Allow the liquid to come to a boil again.
Add the greens. You may need to work in batches, allowing the greens to wilt down to make room for more.
Turn off the SAUTE function.
Secure and lock the lid onto the Instant Pot. Double-check that the valve is closed. Select the MANUAL function and set the timer for 20 minutes. Allow the pressure to release naturally.