Cut the roast into 2-3 chunks and place in the Instant Pot.
Rub the roast with garlic, cumin, and salt and pour onions and salsa verde over the top.
Pour water in, trying to avoid the top of the roast.
Close the Instant Pot and cook on high pressure for 1 1/2 hours. Quick release.
Remove the roast from the pot and shred with two forks.
Pour 1/2 -- 1 cup of liquid from the pot over the meat for the best flavor. Salt and pepper to taste.