Preheat your oven to 375°F (190°C).
Place the chicken breast in a small pot of simmering water and cook for 12-15 minutes until fully cooked, then remove and shred with two forks.
In a small bowl, whisk together the tomato sauce, chili powder, cumin, garlic powder, and sea salt to create the red chili sauce.
Heat the avocado oil in a skillet over medium heat and sauté the diced red onion and green bell pepper until softened and slightly caramelized.
Toss the shredded chicken with the sautéed vegetables and 2 tablespoons of the prepared red chili sauce.
Warm the corn tortillas briefly in a dry pan or microwave to make them pliable.
Spread a spoonful of sauce on the bottom of a small baking dish.
Fill each tortilla with the chicken mixture, roll tightly, and place seam-side down in the dish.
Pour the remaining red chili sauce over the tortillas and sprinkle evenly with the shredded cheddar cheese.
Bake for 15-20 minutes until the sauce is bubbling and the cheese has melted.
Garnish with fresh chopped cilantro before serving warm.