Start by heating the heavy-bottomed pot over medium heat, feeling it warm as you prepare to sauté.
Add a splash of oil, then toss in chopped onions and minced garlic, sautéing until they turn translucent and fragrant, about 5 minutes.
Stir in the chopped tomatoes, cumin, and chili powder, cooking for another 2-3 minutes until the mixture becomes fragrant and slightly thickened.
Pour in the chicken broth and add the shredded cooked chicken, then bring the mixture to a gentle simmer.
Let the soup simmer uncovered for about 20 minutes, allowing the flavors to meld and the broth to deepen in color.
Taste the broth and add a squeeze of lime juice along with salt or additional chili if desired, adjusting the seasoning to your liking.
Ladle the hot soup into bowls and garnish generously with chopped cilantro, slices of creamy avocado, and an extra squeeze of lime for brightness.
Enjoy your vibrant, hearty bowl of Mexican chicken soup, perfect for cozy, satisfying meals.