Preheat your oven to 375°F (190°C).
Poach or grill the chicken breast until the internal temperature reaches 165°F, then shred it thoroughly using two forks.
Heat the olive oil in a medium skillet over medium heat and sauté the diced red onion and bell pepper until they are soft and translucent.
In a small mixing bowl, whisk together the tomato puree, chili powder, cumin, garlic powder, sea salt, and black pepper to create the red chili sauce.
In a separate bowl, combine the shredded chicken with the sautéed vegetables and 2 tablespoons of the prepared chili sauce.
Briefly warm the corn tortillas in a dry skillet or microwave to make them pliable, then fill each with the chicken mixture and roll them up tightly.
Spread a thin layer of sauce on the bottom of a small baking dish, place the tortillas seam-side down, and pour the remaining sauce over the top.
Sprinkle the shredded cheddar cheese over the enchiladas and bake for 15 minutes until the cheese is melted and bubbly.
Garnish with freshly chopped cilantro and serve immediately.