Step 1: Preheat oven to 375 degrees Fahrenheit.
Step 2: Heat oil in a skillet over medium heat. Soften the tortillas one at a time by placing them in hot oil for a few seconds per side. Place on a paper towel to drain.
Step 3: In a bowl, mix the cooked chicken, chopped onions, and half of the shredded cheese.
Step 4: Pour a small amount of enchilada sauce in the bottom of a baking dish.
Step 5: Place the filling onto each tortilla, roll up, and place seam side down in the dish.
Step 6: Cover the rolled tortillas with the remaining enchilada sauce and sprinkle with the remaining cheese.
Step 7: Bake in the preheated oven for 20 minutes, or until cheese is melted and bubbly.
Step 8: Garnish with chopped fresh cilantro and dollops of sour cream before serving.