Preheat the oven to 375 degrees F (190 degrees C). Coat a 9x13-inch baking pan with nonstick spray.
Heat oil in a frying pan over medium-high heat. Saute beef until no longer pink in the center, 5 to 10 minutes. Add onion and cook until transparent, about 2 minutes more. Add black beans, enchilada sauce, and green chiles. Simmer until slightly thickened, about 10 minutes.
Cover the bottom of the prepared pan with a third the beef mixture. Place several tortillas over the meat to cover. Spread half the sour cream. Add another third the meat mixture, cover with tortillas, and spread remaining sour cream on top. Cover with remaining meat mixture.
Top casserole with crushed corn chips and Cheddar cheese, in that order. Sprinkle olives and tomatoes on top of the Cheddar cheese.
Bake in the preheated oven until bubbling, about 35 minutes.