To begin, season the chuck roast with the salt and pepper on both sides.
Press the sauté button on the Instant Pot and add the avocado oil to heat it up.
Place the roast in the hot Instant Pot and sear the meat for about 4 minutes on each side. Press "cancel."
While the meat is searing, combine the tomato sauce, green chilis, apple cider vinegar, tomato paste, oregano, cumin, garlic powder, and red pepper flakes in a small mixing bowl. Whisk together.
When the meat is finished searing, arrange the diced onion and pepper on top of the meat.
Pour the tomato sauce mixture all over the top.
Close and seal the Instant Pot and press the "Meat" button. Adjust the time to run for 35 minutes.
Once the cycle has completed, you can allow the pressure to come down naturally (about 10 minutes) or do a quick release.
Shred or pull apart the beef.
Top with sliced black olives.
Notes
This recipe can be used for up to a 3 lb chuck roast if you are serving a larger family.