Place all of the ingredients for the adobo sauce into the blender and blend for 25-30 seconds until smooth. Then set aside.
Season the chuck roast with the ½ tsp. of salt, ½ tsp. fresh ground pepper, and 1 ½ tsp. chili powder.
Press saute on the Instant Pot. When the front panel reads HOT, add 2 Tbsp. of avocado oil and head for 25 seconds. Then add the roast to the pot and sear on all sides.
Once completely seared to seal in the juices, remove the roast from the Instant Pot. Add a couple of tablespoons from the cup of beef broth and deglaze the bottom of the pot (scrape off any browned bits - - these add flavor but if left on the bottom will cause a burn notice).
Then pour in the remaining broth. into the pot along with the 3 Tbsp. of tomato paste, and the two bay leaves. Whisk the tomato paste with the broth.
Place the roast back into the pot and cover with the sliced onions. Then pour the adobo sauce over the roast.
Close and seal the pot. Cook on High pressure for 1 hour and leave for a natural pressure release for 10-15 minutes.
Release any remaining pressure from the pot after the natural pressure release and open the pot. Carefully move the roast into a shallow baking dish to shred. It should be very fork-tender. Use two forks to pull the roast apart. Save some of the liquid and store it with the meat to keep it moist. ℉
Notes
In several other recipes I have seen for barbacoa thicken the remaining sauce to toss with the meat and then put a pan of the meat under the broiler. I've honestly never done that. We just love the tender meat and can't wait to make it into tacos, burritos, or chilaquiles. The juice is usually spicier than the meat. I do store any leftovers with some of the juices to keep the meat moist.For easy reheating, save a bit more of the juice and put all of the juice and meat into the Instant Pot. Close and seal the lid and cook on high for 1 minute. This is a perfect amount of time to get the meat heated through and ready to serve. Leave in the keep warm state until ready to serve.DON'T HAVE AN INSTANT POT: No worries. Sear your chuck roast in a pan, put it in a crock pot, and cook for 8-9 hours on low or 4-5 hours on high following the directions above. This recipe can also be made in the oven. Put the roast in a Dutch oven or glass baking dish and cook uncovered at 325 ℉ for 3-4 hours or until the chuck roast is fork tender.