Preheat your oven to 375°F (190°C).
Poach or bake the chicken breast until the internal temperature reaches 165°F, then shred it thoroughly using two forks.
Heat the avocado oil in a medium skillet over medium heat and sauté the diced onion and bell pepper until softened and fragrant.
Stir the shredded chicken, ground cumin, garlic powder, sea salt, and black pepper into the skillet with the vegetables to combine flavors.
In a small mixing bowl, whisk together the tomato puree and ancho chili powder to create a smooth, smoky sauce.
Lightly warm the corn tortillas in a dry pan or microwave for 10 seconds to ensure they are pliable and do not crack.
Divide the chicken mixture evenly between the two tortillas, roll them up tightly, and place them seam-side down in a small baking dish.
Pour the ancho chili sauce over the tortillas and top evenly with the shredded Monterey Jack cheese.
Bake for 15 minutes until the sauce is bubbling and the cheese has melted into a golden crust.