Preheat your oven to 375°F (190°C).
Poach the chicken breast in simmering water for 12-15 minutes until fully cooked, then shred with two forks.
In a small mixing bowl, whisk together the tomato puree, chili powder, cumin, garlic powder, onion powder, sea salt, and black pepper to create the red chili sauce.
Lightly brush both sides of the corn tortillas with avocado oil and warm them in a skillet over medium heat for 30 seconds per side until pliable.
Dip each tortilla into the chili sauce to coat, then fill with the shredded chicken and a tablespoon of diced red onion.
Roll the tortillas tightly and place them seam-side down in a small baking dish.
Pour the remaining sauce over the top of the enchiladas and sprinkle evenly with the shredded cheddar cheese.
Bake for 15 minutes until the cheese is melted and the sauce is bubbling.
Remove from the oven and garnish with a dollop of Greek yogurt and fresh cilantro before serving.