Tortilla Soup

Tortilla Strips8 (6-inch) corn tortillas, cut into 1/2-inch-wide stripsVegetable oil spraySalt Soup8 cups low-sodium chicken broth1#189; pounds bone-in, skin-on split chicken breasts, trimmed, skin removed 1 very large white onion (about 1 pound), root end trimmed, peeled and quartered 4 garlic cloves, peeled8-10 sprigs fresh cilantro, plus 2 tablespoons chopped1 sprig fresh oreganoSalt12 ounces tomatoes (about 2 medium), cored and quartered1 tablespoon minced canned chipotle chiles in adobo sauce1 teaspoon canola oil1 avocado, pitted, peeled, and cut into 1/2-inch pieces Lime wedges, for servingFor the tortilla strips: Adjust an oven rack to the middle position and heat the oven to 425 degrees. Spread the tortilla strips on a rimmed baking sheet and lightly coat both sides with vegetable oil spray. Bake until the strips are deep golden brown and crisp, about 10 minutes, rotating the pan and shaking the strips to redistribute halfway through. Season the strips with salt to taste and transfer to a paper towel-lined plate.For the soup: Combine the broth, chicken breasts, 2 of the onion quarters, 2 of the garlic cloves, cilantro sprigs, oregano, and 1/4 teaspoon salt in a Dutch oven. Bring to a simmer over medium-high heat. Cover, reduce the heat to medium-low, and cook until the thickest part of the breasts registers 160-165 degrees on an instant-read thermometer, about 20 minutes.Transfer the chicken breasts to a plate. When the chicken is cool enough to handle, shred the meat into bite-sized pieces, discarding the bones. Meanwhile, pour the broth through a fine-mesh strainer; discard the solids in the strainer.Process the remaining 2 onion quarters, remaining 2 garlic cloves, tomatoes, and chipotle together in a food processor until smooth, 15-20 seconds. Heat the oil in a clean Dutch oven over high heat until just smoking. Add the onion-tomato mixture and 1/8 teaspoon salt and cook, stirring often, until the mixture has darkened in color, about 10 minutes.Stir the strained broth into the pot and bring to#160;a simmer over medium-high heat. Reduce the heat to medium-low and cook until the flavors have blended, about 15 minutes. Add the shredded chicken to the soup and continue to simmer until the chicken is heated through, about 2 minutes.Divide the tortilla strips among 6 bowls, then ladle the soup into the bowls. Top each serving with a portion of the avocado and sprinkle with some of the chopped cilantro. Serve, passing the lime wedges separately.Serves six.Cook's note: If you prefer a soup with milder spiciness, cut the chi#173;potle amount in half. We like this soup as is, but you can add a dollop of low-fat sour cream, minced jalape#241;o, and shredded reduced-fat Monterey Jack cheese.@Recipe nutrition:Nutrition values per serving: 280 calories, 9 g fat (1 g satruated), 28 g carbohydrates, 5 g fiber, 21 g protein, 45 mg cholesterol, 1110 mg sodium."Light and Healthy 2010" by America's Test Kitchen