the.com/onion soup

means a soup built on slowly caramelized onions in broth, usually topped with toasted bread and melted cheese

from straightforward in its naming — 'onion' plus 'soup' — though the dish's fame traces to French cuisine (soupe à l'oignon), where onions were a cheap, humble staple that cooks learned to transform through long, slow cooking into something rich and savory. The gratinée version, crowned with bread and cheese and browned under heat, became the one that traveled the world and stuck in memory.