Prepare the ingredients by chopping onions, bell peppers, and mincing garlic.

In a large pot over medium heat, add olive oil; sauté onions and garlic for 3 minutes until fragrant.

Add chicken breasts and bell peppers; cook for about 5 minutes until slightly browned.

Pour in diced tomatoes (with juice) and chicken broth; bring to a simmer. Reduce heat and let simmer for 20 minutes.

Remove chicken, shred it using two forks, then return it to the pot.

Taste and adjust seasoning with salt and pepper as needed. Serve hot topped with tortilla strips, avocado, and sour cream.