Add all the ingredients to the IP with 2 cups water, give it a good stir and put it on Manual (high pressure) for 20 minutes.
Let the IP natural release or manually vent it after ten minutes, the meat should be super tender.
Saute and stir to dry up the liquid a little. Done.
Notes
If you don't have an Instant Pot then slow cook the beef stove top till tender enough to shred easily, 45-50 minutes then shred and cook the liquid down. If you have a conventional pressure cooker that works well here too!