1. Preheat the broiler. Broil the tomatoes, onions, garlic and chiles in a baking dish 4 inches from the heat for 2 to 3 minutes, or until browned. Turn the vegetables over and broil for 2 to 3 minutes, or until browned. Let cool and peel tomatoes, and chiles. Transfer vegetables in batches to a food processor and pulse until coarsely pureed.
2. Heat oil in a skillet over medium-high heat to 375 degrees. Fry tortilla strips in batches for about 1 1/2 minutes, or until slightly crisp and golden. Transfer to paper towels to drain.
3. Carefully remove all but 3 tablespoons of the oil in the skillet and heat over medium-high heat. Add the puree and the tortillas and stir gently to combine. Add chicken, season with salt and pepper, cook for 5-7 minutes or until the tortillas are heated through but still crisp. Sprinkle with the cheese and top with sour cream.