Place pork, onions, garlic, thyme, 3 cups water into the Instant Pot, cover, and set on manual for 30 minutes.
After cooking, allow to depressurize naturally. Drain, reserve 1 cup of liquid. Remove onions and garlic and discard. Place meat on a cutting board, using two forks pull apart into smaller pieces or shred.
Wipe out instant pot, add 1 tablespoon of olive oil set to “Sauté” setting on high heat. Add the chopped onion, pork, oregano and saute for 10 minutes until the pork begins to brown. Add the tomato sauce, chipotle and reserved liquid. Cook until liquid evaporates.