Preheat your oven to 375°F.
In a small mixing bowl, whisk together the tomato puree, ancho chili powder, ground cumin, garlic powder, onion powder, sea salt, and black pepper to create the sauce.
In a medium bowl, combine the cooked and shredded chicken breast with 2 tablespoons of the prepared ancho sauce and the finely diced red onion.
Warm the corn tortillas in a dry skillet over medium heat for about 30 seconds per side until they are soft and pliable.
Place a portion of the chicken mixture into the center of each tortilla, roll them up tightly, and place them seam-side down in a small oven-safe baking dish.
Pour the remaining ancho chili sauce evenly over the top of the rolled tortillas.
Sprinkle the shredded sharp cheddar cheese over the sauce-covered tortillas.
Bake in the preheated oven for 15 minutes, or until the sauce is bubbling and the cheese has completely melted.
Remove from the oven and garnish with fresh chopped cilantro before serving.