Preheat your oven to 375°F (190°C). If you haven't cooked the chicken yet, boil or bake it until fully cooked, then shred using two forks or your hands.

Heat a skillet over medium heat and add the vegetable oil. Once hot, add the chopped onion and minced garlic. Sauté until soft and fragrant, about 3-4 minutes.

Add the shredded chicken to the skillet with the sautéed onions and garlic. Season with cumin, chili powder, salt, and pepper. Stir together and cook for another 3-5 minutes.

Pour a small amount of red enchilada sauce into the bottom of a 9x13-inch baking dish to prevent sticking.

Take a flour tortilla and place a generous spoonful of the chicken mixture in the center. Sprinkle some shredded Monterey Jack cheese on top, then roll the tortilla tightly. Place seam side down in the baking dish. Repeat until all tortillas are filled.

Pour the remaining enchilada sauce over the top, covering each enchilada well. Sprinkle the rest of the shredded cheese on top.

Cover the dish with foil and bake for 20-25 minutes. Remove foil and bake for an additional 5-10 minutes until the cheese is bubbly and slightly golden.

Let rest for 5 minutes before serving. Garnish with chopped cilantro and serve with sour cream.