Preheat oven to 350°F (175°C).
Heat oil in skillet and cook chicken 5–7 minutes per side until done.
Cube chicken and return to pan.
Add onion, 1 cup cheese, sour cream, parsley, oregano, and pepper. Cook on low until melted.
Stir in tomato sauce, green pepper, garlic, chili powder, salt, and water if needed.
Spoon filling onto tortillas and roll tightly.
Place seam-side down in baking dish.
Pour taco sauce over enchiladas.
Top with remaining cheese.
Bake 20 minutes until hot and cheese melts.
Rest 5 minutes and serve.