Preheat your oven to 375°F (190°C).
In a small saucepan, combine the tomato puree, ancho chili powder, cumin, garlic powder, onion powder, sea salt, and black pepper. Simmer over low heat for 5 minutes to develop the flavors.
Heat avocado oil in a skillet over medium heat and sauté the diced bell peppers and onions until they are soft and slightly caramelized.
In a mixing bowl, combine the cooked shredded chicken breast with the sautéed vegetables and 2 tablespoons of the prepared ancho sauce.
Briefly warm the corn tortillas in a dry pan or microwave to make them pliable.
Place a portion of the chicken and vegetable mixture into each tortilla, roll them up tightly, and place them seam-side down in a small baking dish.
Pour the remaining ancho chili sauce over the tortillas and sprinkle evenly with the shredded Monterey Jack cheese.
Bake for 12-15 minutes until the sauce is bubbling and the cheese has melted completely.
Garnish with freshly chopped cilantro before serving.