Preheat oven to 425°.
Heat a Dutch oven coated with cooking spray over medium-high heat. Add chicken, and sauté 2 minutes. Remove chicken; keep warm.
Add onion to pan; cook 4 minutes, stirring frequently. Add garlic; sauté 15 seconds. Add broth, chipotle chili, and chili powder. Bring to a boil; cover, reduce heat, and simmer 20 minutes.
Stir in tomato and next 3 ingredients; add chicken. Cover, reduce heat, and simmer 20 minutes.
While soup simmers, cut tortillas into 1/4 x 2-inch strips. Place on a baking sheet in a single layer, and coat lightly with cooking spray. Bake at 425° for 8 to 10 minutes or until lightly browned. Cool completely.
Ladle soup into bowls; sprinkle servings evenly with cilantro and tortilla strips.