Cook chicken in a nonstick skillet over medium heat, until no longer pink and juices run clear, about 10 minutes per side. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C). Drain excess fat. Cube chicken and return to skillet. Add onion, sour cream, 1 cup Cheddar cheese, parsley, oregano, and ground black pepper. Heat until cheese melts, about 3 minutes. Stir in salt, tomato sauce, water, chili powder, green bell pepper, red bell pepper, garlic, and black beans.
Roll even amounts of mixture into tortillas. Arrange in a 9x13-inch baking dish. Cover with taco sauce and 3/4 cup Cheddar cheese.
Bake uncovered in preheated oven until cheese is melted and sauce is bubbling, about 20 minutes. Cool 10 minutes before serving.
