Sauté the aromatics: Heat olive oil in a large pot over medium heat. Add onion and cook 3–4 minutes until softened.
Stir in garlic and cook 30 seconds until fragrant.
Season the base: Sprinkle in taco seasoning, cumin, and chili powder. Stir for 30 seconds to bloom the spices.
Add liquids and tomatoes: Pour in chicken broth. Stir in diced tomatoes, tomatoes with green chiles, and tomato paste until dissolved.
Add chicken and simmer: Nestle raw chicken breasts into the pot.
Bring to a gentle boil, then reduce to a simmer. Cover and cook 12–16 minutes, or until chicken reaches 165°F and shreds easily.
Shred the chicken: Transfer chicken to a plate and shred with two forks. Return the shredded chicken to the pot.
Beans and corn: Stir in black beans, pinto beans, and corn.
Simmer uncovered 5–10 minutes to thicken slightly and let flavors meld.
Brighten and adjust: Stir in lime juice. Taste and season with salt and pepper. If you like it spicier, add a pinch of cayenne or hot sauce.
Serve with toppings: Ladle into bowls and finish with your favorite toppings.
For extra protein, use a spoonful of plain Greek yogurt instead of sour cream.