Preheat your oven to 375°F (190°C).
Dice the red bell pepper and yellow onion finely.
Heat avocado oil in a small skillet over medium heat and sauté the peppers and onions until they are soft and translucent.
Shred the cooked chicken breast and place it in a mixing bowl, seasoning with sea salt, black pepper, and chili powder.
In a separate small bowl, whisk together the red enchilada sauce and plain Greek yogurt until a smooth, creamy sauce forms.
Cut the corn tortillas into bite-sized strips or quarters.
In a small oven-safe baking dish, layer half of the tortilla pieces, followed by the sautéed vegetables, the seasoned chicken, and half of the creamy sauce.
Add the remaining tortilla pieces and the rest of the sauce, then top evenly with shredded Monterey Jack cheese.
Bake for 15 to 20 minutes until the cheese is melted and the edges are bubbling.
Garnish with freshly chopped cilantro and serve warm.