Preheat your oven to 375°F and lightly grease a small baking dish with a touch of oil.
Place the chicken breast in a pot of simmering water for 12 minutes until fully cooked, then shred it using two forks.
Heat the olive oil in a skillet over medium heat and sauté the diced white onion until it becomes soft and translucent.
In a medium bowl, combine the shredded chicken, sautéed onions, cumin, garlic powder, sea salt, and black pepper.
In a separate small bowl, whisk together the tomato sauce and chili powder to create a clean, homemade red chili sauce.
Warm the corn tortillas briefly in a dry pan to make them pliable, then dip each one into the sauce to coat both sides.
Fill each tortilla with the chicken mixture, roll them up tightly, and place them seam-side down in the baking dish.
Pour the remaining red chili sauce over the top of the rolled tortillas and sprinkle evenly with the sharp cheddar cheese.
Bake for 15 minutes until the sauce is bubbling and the cheese has melted into a golden layer.
Garnish the finished enchiladas with fresh cilantro and serve immediately while hot.