Cut the steak down into 4 large, equal pieces then season generously with kosher salt and pepper.
Press the 'saute' button and add 2 tbsp of the avocado oil to the IP. When the oil is hot, sear the steak (you may need to do this in 2 batches so you don't overcrowd the pan) so that a deep brown crust forms on both sides, 3-4 minutes per side.
Once all of the steak is browned, click the 'cancel' button to turn off the saute function. Pour in 1 cup of the salsa verde and close the lid on the IP. Turn the valve at the top so that it is sealed. Press the 'manual' button, then set the time to 45 minutes. Walk away from the IP and let it do it's thing.
When the cook time is complete, manually release the pressure by carefully turning the valve to vent. Allow all the of the steam to release (this takes a few minutes) before carefully opening the IP. Using two forks, shred the beef.