It's quick and easy and tastes like French restaurant food—from your own kitchen!
Heat broiler. Bring low-sodium beef broth and caramelized onions to a simmer over medium; season with coarse salt and ground pepper. Top thick-sliced country bread with grated Gruyere cheese and season with pepper; broil until toasted. Serve soup with cheese toasts.
If you make the caramelized onions in advance, putting this soup together is a snap.