Prepare the chicken by boiling or baking until fully cooked, then shred it.
Heat a skillet over medium heat and add vegetable oil. Sauté onion and garlic until soft and fragrant, about 3-4 minutes.
Add shredded chicken to the skillet. Season with cumin, chili powder, salt, and pepper. Cook 3-5 minutes while stirring.
Pour a small amount of enchilada sauce into the bottom of a baking dish.
Place a spoonful of chicken mixture in center of each flour tortilla, sprinkle with cheese, roll tightly and place seam side down in baking dish.
Pour remaining enchilada sauce over rolled enchiladas and sprinkle with remaining cheese.
Cover with foil and bake at 375°F (190°C) for 20-25 minutes.
Remove foil and bake additional 5-10 minutes until cheese is bubbly and golden.
Let enchiladas rest for a few minutes before serving.
Garnish with chopped cilantro and serve with sour cream.