Start by adding all the chipotle sauce ingredients into a food processor or blender. Blend these until you achieve a smooth consistency. Once the sauce is ready, set it aside; your taste buds are going to thank you later!

Next, you’ll want to trim off any large sections of fat from the chuck roast. Cut the meat into 6-8 large chunks for even cooking. Sprinkle the pieces with kosher salt and black pepper, making sure each piece is well seasoned.

Set your Instant Pot to the "Sauté" function and add vegetable oil. Once the oil is shimmering, add the seasoned beef chunks. Brown them on all sides for about a minute per side—this takes a little time, but it’s essential for enhancing the flavor. Depending on how big your pieces are, you might need to do this in batches. Once browned, transfer the beef to a plate.

In the same pot, add the diced onion. Sauté for about 2-3 minutes or until the onions soften and become translucent. This adds a great base flavor to your barbacoa.

Pour in one cup of beef broth, using a wooden spoon to scrape any browned bits from the bottom of the pot. This process not only helps in cleaning the pot but also adds depth to your sauce.

Now, stir in the diced green chiles, tomato paste, and bay leaves. Once these are well combined, press "Cancel" to stop the sauté. Return the browned beef pieces to the pot, then pour the blended chipotle sauce over the top. Don’t forget to toss in the lime halves for an extra kick of flavor!

Secure the lid on your Instant Pot, ensuring that the valve is set to "sealing." Select "Manual" or "Pressure Cook" and adjust the timer to 60 minutes.

Once the cooking cycle is done, carefully switch the valve to "venting" for a quick pressure release. Wait for the steam to fully escape and the pin to drop before removing the lid. Discard the bay leaves.

Transfer the pieces of beef to a large bowl and shred them using two forks. You’ll want to discard any large pieces of fat but keep all that tender goodness!

If you prefer a thicker sauce, mix 2 tablespoons of cornstarch with 3 tablespoons of water in a small bowl until smooth. Pour this mixture back into the pot and select "Sauté." Stir frequently until the sauce thickens to your desired consistency.

For a delightful texture, line a baking sheet with foil and preheat your broiler to high. Spread the shredded beef out on the sheet in an even layer. Broil for several minutes, stirring halfway through, until the beef reaches your desired level of crispiness.