Preheat your oven to 375°F and lightly grease a small baking dish with a touch of oil.
Poach the chicken breast in simmering water for 12 minutes until fully cooked, then shred it finely using two forks.
Sauté the diced yellow onion in olive oil over medium heat until it becomes soft and translucent.
In a small bowl, whisk together the tomato puree, chili powder, cumin, garlic powder, salt, and pepper to create a smooth sauce.
Toss the shredded chicken and sautéed onions with two tablespoons of the prepared red chili sauce.
Warm the corn tortillas slightly, dip each into the sauce, fill with the chicken mixture, and roll them up tightly.
Arrange the tortillas seam-side down in the dish, pour the remaining sauce over the top, and sprinkle with shredded cheddar.
Bake for 15 minutes until the cheese is melted and the edges are slightly crisp and golden.