Preheat your oven to 375°F.
Poach or pan-sear the chicken breast until the internal temperature reaches 165°F, then shred it thoroughly with two forks.
In a small skillet, heat the olive oil over medium heat and sauté the diced yellow onion until it becomes soft and translucent.
In a medium bowl, combine the shredded chicken with the sautéed onions, chili powder, ground cumin, garlic powder, sea salt, and black pepper.
Warm the corn tortillas briefly in a dry pan or the microwave until they are soft and pliable.
Spread 2 tablespoons of the red enchilada sauce across the bottom of a small baking dish to prevent sticking.
Place a portion of the chicken mixture into each tortilla, roll them up tightly, and arrange them seam-side down in the baking dish.
Pour the remaining enchilada sauce evenly over the tortillas and top with the shredded cheddar cheese.
Bake for 15 to 20 minutes until the sauce is bubbling and the cheese has melted completely.
Garnish with freshly chopped cilantro and serve immediately while hot.