1. Prepare the chicken by boiling or baking until fully cooked, then shred it using two forks or your hands.
2. Heat a skillet over medium heat and add the vegetable oil. Sauté the chopped onion and minced garlic until soft and fragrant, about 3-4 minutes.
3. Add the shredded chicken to the skillet with the sautéed onion and garlic. Season with cumin, chili powder, salt, and pepper. Stir and cook for another 3-5 minutes.
4. Pour a small amount of red enchilada sauce into the bottom of a baking dish to prevent sticking.
5. Place a flour tortilla on a flat surface and add a generous spoonful of the chicken mixture in the center. Sprinkle with shredded cheese and roll tightly. Place the rolled tortilla seam-side down in the baking dish. Repeat this process with the remaining tortillas.
6. Pour the remaining enchilada sauce over the rolled tortillas and sprinkle with the rest of the shredded cheese.
7. Cover the dish with foil and bake in a preheated oven at 375°F (190°C) for 20-25 minutes.
8. Remove the foil and bake for an additional 5-10 minutes or until the cheese is bubbly and slightly golden.
9. Allow the enchiladas to rest for a few minutes before serving. Garnish with chopped cilantro and serve with sour cream.