Set Instant Pot to saute mode and wait for display to read "Hot." Add olive oil and roast. Brown roast on both sides and then press "Cancel" to turn saute off.
Add remaining ingredients to the pot.
Secure lid and turn valve to sealing. Set to high pressure for 80 minutes. When the cook time has finished, allow for a natural pressure release.
Carefully remove meat from the pot to shred. Once meat has been shredded, combine with juices and seasonings in the pot.
Serve in flour tortillas with your favorite taco toppings.