In a Dutch oven over medium heat, add olive oil and when it gets hot, add onions, jalapeno peppers, tomatoes, garlic, chipotle purée, oregano and cumin. Sauté the ingredients until softened about 8 to 10 minutes, stirring constantly. If more oil is needed, add a little.
Pour in 2 cups of chicken broth and cook for 20 minutes.
Transfer the mixture into the jar of a blender. Cover but remove the cap so the steam can escape and place a clean dish towel on top; process on low speed until very smooth.
Return the mixture to the Dutch oven, increase the heat to high and pour in the remaining 4 cups of chicken broth. Season with salt and pepper and bring to a boil.
Add chicken breasts, reduce the heat to medium and simmer until done, about 20 minutes.
Meanwhile, prep the flour tortillas by cutting them in half. Take the two halves and cut them in half again. Take a section and cut it into strips of about ½-inch wide; set aside.
In a cast iron pan, add canola oil and bring the temperature to between 350ºF to 360ºF. Working in batches, add the strips in a single layer and flip them until golden brown, about 45 seconds.
Transfer them to a plate lined with paper towels to remove any excess oil. Set aside while frying the remaining strips.
Back to the soup… Remove the chicken and place it in the bowl of a stand mixer with the paddle attachment on; process on medium speed until shredded, about 30 to 45 seconds. Return the shredded chicken back to the Dutch oven, pour in the lime juice and stir well. Bring it back to a gentle simmer and let it cook for 5 minutes.
To serve, ladle the soup into serving bowls and garnish with ¼ cup Oaxaca cheese, a couple of slices of avocado, a few strips of fried tortilla, a big dollop of crema and for the finishing touch, sprinkle on some fresh chopped cilantro.