Combine the sour cream, chicken broth, lemon juice, 2 teaspoons of canola oil, sea salt and freshly cracked pepper, to taste, and the avocado together in a bowl then mix with an immersion blender (or food processor) until creamy and smooth. Set aside.
Heat 1/2 teaspoon in a pan over medium high heat and cook the tortilla for 2 minutes on each side or until golden brown. Repeat procedure for the remaining tortillas. Set aside.
Once the tortillas are cooked, add another 2 teaspoons of oil to the skillet and heat it over medium heat. Cook the onion for 4-5 minutes, stirring often. Add the shredded chicken, black beans, cumin, and coriander to the chicken mixture. Cook, stirring often, for 2-3 minutes or until mixture is warmed through. Season with sea salt and freshly cracked pepper, to taste.
Layer the chicken mixture on top of a crispy tortilla then add some lettuce, tomatoes, cilantro, avocado sauce, and cotija cheese crumbles. Serve immediately. Enjoy.