Preheat your oven to 375°F and lightly grease a small baking dish with avocado oil.
In a small saucepan over medium heat, whisk together the tomato puree, chicken broth, chili powder, cumin, garlic powder, sea salt, and black pepper until simmering.
Sauté the diced white onion in a separate pan with a splash of water until translucent, then toss with the shredded cooked chicken and two tablespoons of the prepared red sauce.
Warm the corn tortillas briefly in a dry skillet over medium heat for 30 seconds per side until they are soft and pliable.
Fill each tortilla with half of the chicken and onion mixture, roll them up tightly, and place them seam-side down in the baking dish.
Pour the remaining red chili sauce evenly over the tortillas and sprinkle the shredded cheddar cheese across the top.
Bake for 15 to 20 minutes until the sauce is bubbling and the cheese has completely melted and turned golden.