In a large Dutch oven, combine chicken breast, water, celery, and yellow onion. Bring to a boil over medium-high heat; reduce heat, and simmer 45 minutes, or until chicken is tender. Remove chicken from broth; reserve broth. Let chicken cool slightly; skin and bone chicken. Shred chicken, and set aside. Strain broth, discarding vegetables, set aside.
In Dutch oven, melt butter over medium-high heat; add sweet onion, bell pepper, jalapeÃ±os, and garlic. Cook 6 to 7 minutes, or until tender. Stir in flour, and cook 2 minutes, stirring constantly. Add tomatoes, 10 cups reserved chicken broth, shredded chicken, cilantro, cumin, salt, and chili powder. Bring to a boil, reduce heat, and simmer 20 minutes. Stir in lime juice.
In a small skillet, heat vegetable oil over medium-high heat. Fry tortilla strips, in batches, until crispy; drain on paper towels.
Ladle soup into bowls, top with crispy tortilla strips. Garnish with a dollop of sour cream and cilantro, if desired.