1. Heat the olive oil in a large stockpot over medium heat. Add the onions and garlic and saute until tender and golden, 5 minutes. Stir in the cumin, coriander, and chile powder and cook until fragrant, 1 minute. Add the tomatoes and chicken broth, season with salt and pepper, and bring to a simmer over high heat. Add the chicken breasts and reduce the heat to medium-low. Simmer uncovered (don't let the soup come to a boil), stirring occasionally, until the chicken is just barely cooked through, about 12 minutes. Remove the chicken to a plate and let sit until cool enough to handle. Keep the soup gently simmering over medium-low heat.
2. Meanwhile, pour the canola oil to a depth of 1 inch into a medium-size skillet and heat over medium-high heat. Line a plate with a couple of paper towels. When the oil is hot, add the tortilla strips in batches and fry, stirring often, until crisp and lightly colored, about 2 minutes. Remove with a slotted spoon to the plate and sprinkle lightly with salt while they are still hot.
3. Shred the cooled chicken, and stir it and the lime juice into the soup.
4. Ladle the soup into bowls and top with the fried tortilla strips, along with your choice of avocado, shredded cheese, cilantro, and salsa. Serve with lime wedges.