Set the Instant Pot to 'Sauté' mode and add onions and garlic.
Add diced carrots and bell pepper to the pot, stirring occasionally.
Mix in the diced tomatoes, chili powder, cumin, salt, and black pepper.
Place the chicken breasts on top of the vegetable mixture, followed by chicken broth.
Close the lid and set the Instant Pot to 'Manual' for 10 minutes.
Once the timer goes off, quick-release the pressure and carefully open the lid.
Remove the chicken and shred it using two forks.
Return the shredded chicken to the pot and stir in tortilla strips.
Simmer on 'Sauté' mode for an additional 3-5 minutes, adjusting consistency if necessary.
Serve hot, garnished with diced avocado, shredded cheese, and fresh cilantro.