I heat the oil in a large pot over medium heat until it shimmers. Then I add the sliced tortillas in batches and fry for 45–60 seconds, until light golden and crispy. I transfer them to a paper towel-lined plate and sprinkle lightly with salt. They’ll become the crunchy topping later.
I pour off most of the oil, leaving about 3 tablespoons in the pot. Then I add the diced onion, poblanos, garlic, and chopped cilantro stems. I cook them until soft and lightly browned, about 8 minutes. Next, I stir in the chili powder, cumin, oregano, and salt, cooking for another minute to release all the aroma and flavor.
I add the chicken broth, shredded chicken, frozen corn, crushed tomatoes, and water. Once it comes to a boil, I lower the heat to a gentle simmer and cook for 15–20 minutes. Just before serving, I stir in the lime juice and adjust seasoning with more salt or chili powder if needed.