Start by heating olive oil in a large skillet over medium heat. Once hot, add the chopped onions and sauté for about 3 minutes until they start to soften. Stir in the minced garlic and cook for 30 seconds, just until fragrant. Then turn off the heat to avoid overcooking the aromatics.
Add the cooked shredded chicken to the skillet along with the rinsed black beans and undrained green chiles. Sprinkle in the chili powder, cumin, oregano, and salt. Pour in ½ cup of enchilada sauce and stir well to combine. This flavorful filling is the heart of your enchiladas.
Lightly grease a 9×13-inch baking dish, then spread ½ cup of enchilada sauce on the bottom. Lay out a tortilla and spoon about ½ cup of the chicken mixture onto the center, slightly off-center for easier rolling. Sprinkle about ⅓ cup of shredded cheese on top of the filling.
Roll the tortilla up tightly and place it seam-side down into the dish. Repeat this step with the remaining tortillas, filling, and cheese. Once all enchiladas are in the pan, pour the remaining enchilada sauce over the top, making sure they’re well coated. Finish by scattering the rest of the shredded cheese across the top.
Preheat your oven to 350°F. Bake the enchiladas uncovered for 20 to 25 minutes, or until hot and bubbly. Once done, let them rest for about 5 minutes to settle before serving. You can add toppings like fresh cilantro, avocado slices, sour cream, or pico de gallo to give each serving a bright, fresh twist.