Preheat your oven to 375°F (190°C).
In a small saucepan over medium heat, whisk together the tomato puree, water, chili powder, ground cumin, sea salt, and garlic powder.
Simmer the sauce for 5 minutes until the flavors meld and it thickens slightly, then set aside.
In a small skillet, sauté the diced white onion in olive oil until translucent and soft.
Add the cooked shredded chicken breast to the skillet with the onions, tossing to warm through and combine.
Lightly warm the corn tortillas in a dry pan or microwave for 10 seconds to make them pliable.
Place half of the chicken and onion mixture into each tortilla, roll them tightly, and place them seam-side down in a small baking dish.
Pour the prepared red chili sauce evenly over the tortillas and top with the shredded sharp cheddar cheese.
Bake for 12 to 15 minutes until the cheese is melted and the sauce is bubbling.
Garnish with fresh chopped cilantro before serving.