Gather all ingredients and equipment, setting everything within reach to streamline the process.
Heat the large heavy-bottomed pot over medium heat, then add a splash of oil. Sauté chopped onions and minced garlic until translucent and fragrant, about 5 minutes, filling your kitchen with a warm aroma.
Add the chicken breasts to the pot and pour in the chicken broth. Bring the mixture to a gentle simmer, then cook for about 15 minutes until the chicken is cooked through and tender.
Remove the cooked chicken from the broth and shred it into bite-sized pieces using two forks. Return the shredded chicken to the pot, stirring to combine.
Stir in the corn kernels, diced tomatoes with their juices, and chili powder. Let everything simmer together for another 10 minutes, allowing flavors to meld and the soup to thicken slightly.
Pour in the lime juice and taste the broth. Adjust seasoning with salt, pepper, or more lime juice if needed to brighten the flavors.
Ladle the hot soup into bowls and garnish generously with chopped cilantro, sliced avocado, and an extra squeeze of lime for a fresh, vibrant finish.