Sauté the onion and garlic until softened and fragrant.
Add the chicken broth to the pot.
Blend the tomatoes and cilantro until completely smooth. Add a splash of water or a little chicken broth if needed to help everything blend.
Pour the tomato mixture into the pot. Bring to a boil, then reduce the heat to medium and let it simmer for 10–15 minutes so the tomatoes and cilantro cook through.
Stir in the taco seasoning (4tbsp) and chicken bouillon (2tbsp). You can start with less and add more to taste.
Add the shredded chicken (if using), beans, and corn. Simmer for another 10–15 minutes so the flavors come together.
If you’re starting with raw chicken breasts or thighs, add them while the broth is boiling. Once cooked through, remove them, shred, and return the chicken to the soup.
Temper the sour cream to keep it from curdling. Place the sour cream in a bowl and slowly whisk in a few spoonfuls of the hot soup. Continue adding a little soup at a time until the sour cream is warm and smooth, then stir it back into the pot.
Taste and adjust as needed. Add more salt, taco seasoning, broth or sour cream according to your taste and preference. You can’t go wrong.
Squeeze in some lime juice according to taste, stir, and serve.
