Heat the oven to 400°F. Toss tortilla strips with 1 tablespoon oil and 1/4 teaspoon salt, spread on a baking sheet and bake for 8 to 10 minutes, stirring once, until crisp.
Heat the remaining oil in a soup pot and cook onion for 5 minutes. Add garlic, chipotle and cumin for 30 seconds, then add tomatoes and 1 cup broth; simmer for 5 minutes.
Blend the tomato mixture smooth with an immersion blender. Add the remaining broth, chicken and remaining salt.
Simmer gently for 18 to 22 minutes until the chicken reaches 165°F. Remove, shred and return the meat to the pot.
Stir in lime juice and divide among bowls. Add the measured baked tortilla strips just before eating.