Preheat your oven to 375°F (190°C).
Heat the avocado oil in a small skillet over medium heat and sauté the diced red onion and bell pepper until they are soft and translucent.
In a medium mixing bowl, whisk together the red enchilada sauce, Greek yogurt, chili powder, garlic powder, sea salt, and black pepper until smooth.
Fold the cooked shredded chicken and the sautéed vegetables into the sauce mixture until everything is thoroughly coated.
Cut the corn tortillas into small strips or bite-sized squares.
In a small oven-safe baking dish, spread a thin layer of the chicken mixture on the bottom, followed by a layer of tortilla pieces.
Continue layering the remaining chicken mixture and tortillas, finishing with the chicken mixture on top.
Sprinkle the shredded sharp cheddar cheese evenly over the top of the bake.
Place in the oven and bake for 15 to 20 minutes until the cheese is melted and the edges are bubbling.
Remove from the oven and let it sit for 5 minutes before garnishing with freshly chopped cilantro and serving.