Season the beef on all sides with salt and pepper. Put the oil in the Instant Pot and push “Sauté”, then push “Adjust” to increase the heat to “More”. When the oil is hot, add the beef and brown for 5 minutes, turning the pieces over halfway through.
Add the beef broth, onion, and garlic cloves, and press “Keep Warm/Cancel”. Place the lid on the Instant Pot, making sure the valve is turned to “Sealing”. Push “Manual” and use the plus button to increase the time to 40 minutes. Cooking will begin automatically.
When the time is up, push “Keep Warm/Cancel” and let the pressure release naturally (this takes 15-20 minutes; a manual pressure release can negatively impact the texture of the meat).
Remove the lid, transfer the meat to a plate, and shred it with two forks. Taste and adjust seasonings as desired. Serve hot alongside corn or flour tortillas, diced onion, chopped cilantro, lime wedges, and Molli Sonora Taqueria hot sauce. Provecho!