Preheat oven to 350°F (175°C). Grease a 9×13-inch baking dish.
In a large skillet, heat avocado oil over medium-high heat. Add diced onion and sauté for 5 minutes, or until translucent.
Add diced chicken to the skillet. Season with salt and pepper. Cook for 7-8 minutes, stirring occasionally, until chicken is cooked through and lightly browned.
Stir in diced green chiles and black beans. Remove from heat.
Warm tortillas in the microwave for about 30 seconds to make them pliable.
Spoon chicken mixture evenly onto each tortilla. Roll up tightly and place seam-side down in the prepared baking dish.
Pour red enchilada sauce evenly over the rolled tortillas.
Sprinkle shredded cheese over the top.
Bake uncovered for 20-25 minutes, or until the cheese is melted and bubbly.
Garnish with optional toppings such as fresh cilantro, chopped red onions, diced avocado, sour cream, and/or crumbled cotija cheese before serving.