Preheat oven to 350 degrees F (175 degrees C). Lightly grease a medium casserole dish.
Heat the oil in a skillet over medium heat, and saute the onion, celery, pepper, mushrooms, and garlic until tender. Season with salt and pepper. Mix in the corn flake crumbs and soup. Transfer to the prepared casserole dish.
Bake 30 minutes in the preheated oven, until lightly browned.
