Preheat your oven to 375°F (190°C) and lightly grease a small baking dish.
In a small saucepan over medium heat, combine the tomato puree, chili powder, cumin, garlic powder, onion powder, sea salt, and black pepper. Simmer for 5 minutes to allow flavors to meld, then set aside.
Heat the olive oil in a skillet over medium heat. Add the diced red onion and green bell pepper, sautéing until tender and slightly caramelized, about 5-6 minutes.
In a mixing bowl, combine the cooked shredded chicken breast with the sautéed onions and peppers, adding 2 tablespoons of the prepared red chili sauce to the mixture to keep it moist.
Warm the corn tortillas in a dry skillet or microwave for 10 seconds until pliable.
Dip each tortilla into the red chili sauce to coat both sides. Place a portion of the chicken and vegetable mixture in the center of each tortilla, roll tightly, and place seam-side down in the baking dish.
Pour the remaining red chili sauce over the top of the enchiladas and sprinkle evenly with the shredded cheddar cheese.
Bake for 15-20 minutes until the sauce is bubbling and the cheese has completely melted.
Garnish with freshly chopped cilantro before serving warm.