Poach the chicken breast in simmering water for 12-15 minutes until cooked through, then shred with two forks and set aside.
Heat the olive oil in a skillet over medium heat and sauté the diced onion and bell pepper until softened and slightly caramelized.
Stir the shredded chicken into the skillet along with half of the chili powder, half of the cumin, the sea salt, and the black pepper.
In a small bowl, whisk together the tomato puree, garlic powder, and the remaining chili powder and cumin to create the red chili sauce.
Lightly warm the corn tortillas in a dry pan for 30 seconds per side to make them pliable.
Dip each tortilla into the sauce to coat, fill with the chicken and pepper mixture, roll tightly, and place seam-side down in a small baking dish.
Pour the remaining sauce over the rolled enchiladas and sprinkle evenly with the shredded sharp cheddar cheese.
Bake at 375°F for 15 minutes until the sauce is bubbling and the cheese is completely melted.
Garnish with freshly chopped cilantro and serve immediately.