Season the chicken breasts and sear both sides on the saute setting with some olive oil.
Remove the chicken from the pot, then add the garlic and onion and saute while scraping any browned bits off the bottom of the insert.
Add the diced tomatoes, chicken stock, remaining seasonings and give a good stir. Place the chicken on top of the sauce.
Cook on high pressure for 10 minutes.
Remove the cooked chicken breasts and set the Instant Pot to saute. Allow the leftover sauce to reduce while you shred the chicken with a couple of forks.
Put the shredded chicken back into the sauce, add the lime juice and the cilantro, then stir well to combine it all.