Set the Instant Pot to "Saute," and allow to get hot. Add the oil. Then add the onions and stir for 1-2 minutes until soft.
1 tablespoon cooking oil, ½ cup white onion
Add the beef and garlic. Continue to stir until all sides of the beef are browned.
2 garlic cloves
Add the taco seasoning, beef broth, and tomatoes and green chiles (undrained). Close the lid and set to "Sealing." Choose the "Meat/Stew" option and set for 40 minutes. If your pressure cooker doesn't have a meat/stew button, choose manual/pressure cook on high for 40 minutes.
1 ounce taco seasoning, 1 cup low-sodium beef broth, 10 ounces diced tomatoes and green chiles
After the meat cooks for 40 minutes, allow the pressure cooker to complete a full pressure release. Next, remove the lid and use two forks to shred the beef.
Serve the beef on tortillas, shells, or chips. Top with tomatoes, onions, cilantro, sour cream, or your other favorites.
Reserve the juice from the Instant Pot for any leftover beef. Place remaining beef in juice and transfer to an airtight container. Store in the refrigerator for up to three days.
Notes
*We used a 6-Quart Duo Instant Pot for this recipe and have not tried other sizes or models. Substitutions or adjustments may change the outcome of the dish.*In the event you are concerned about sodium intake, consider using a low-sodium or sodium-free taco seasoning.*Step 1 of the instructions regarding seasoning the meat can be done in advance. Simply season the meat and place in a sealed container in the refrigerator for 1-3 hours ahead of time.*Calories are approximate and only account for the the ingredients listed minus the optional garnishes.