To begin, place onions, peppers, and garlic in the bottom of the inner pot bowl of the Instant Pot. Lay chicken breasts on top of the veggies, and sprinkle the spices over the top of the chicken.
Top the chicken with the canned tomatoes and pour the broth into the pot’s side without disturbing the chicken. It’s okay if the onions float to the surface.
Set the Instant Pot on Pressure Cook for 5 mins and press START. It will take about 20 minutes to build pressure before the 5 mins cook time, and this is where you might like to catch up on a bit of telly or make the tortilla strips.
Once the time is up press CANCEL and let it sit for 10 minutes to allow the chicken to cook and soften to a shreddable texture. Only attempt to open the lid after this time.
After 10 minutes, carefully release the vent and open the lid. Using tongs, remove the chicken and transfer it onto a plate, and let it cool for about 5 minutes, then shred it up using two forks.
Add some of the broth to coat the shreds and set it aside. Optional step-Take some of the liquid into a small bowl, add corn meal and mix it into a paste, then add that back into the pot; it will thicken a little. Return the chicken to the pot, give it a big stir, and add salt and pepper if needed. Serve with your favourite low carb toppings.