French Onion Soup
To make French onion soup, cook thinly sliced onions in butter very slowly — 45 minutes or more — until deep golden brown and jammy. This slow caramelization is the whole soup. Deglaze with a splash of wine, add good beef stock, and simmer to meld. Ladle into bowls, top each with a slice of toasted baguette and grated Gruyère, and broil until bubbling and golden. Don't rush the onions; that's where all the flavour is.
French onion soup is proof that patience is a flavour. It’s built from the cheapest ingredient in the kitchen — onions — but cooked slowly until they turn deep, sweet, and mahogany, they become something rich and luxurious. Topped with a bubbling raft of cheese-toast, it’s one of the great cozy dinners of winter.
The onions are the whole soup
There is no shortcut here, and anyone who tells you onions caramelize in 10 minutes is lying. Give them 45 minutes to an hour over medium-low heat, stirring regularly, until they collapse and turn from pale to golden to deep, jammy brown. That colour — that slow, patient caramelization — is the flavour of the soup. Rush it on high heat and you burn them instead. Put on some music; it’s worth the wait.
Good stock matters
With so few ingredients, the beef stock does a lot of the work — use the best you can. A splash of dry white wine or sherry to deglaze lifts everything and scrapes all the browned flavour off the bottom of the pot.
The cheese-toast lid
Gruyère is the classic — nutty, savoury, and a beautiful melter. Toast sturdy baguette slices so they don’t dissolve, float them on the soup, pile on the cheese, and broil until bubbling and golden. No oven-safe bowls? Broil the cheese toasts on a tray and float one on each bowl.
Make it yours
- Extra depth: a spoon of sherry or brandy, or a splash of Worcestershire.
- Herby: more thyme, or a bay leaf and a parmesan rind in the simmer.
- Vegetarian: a rich mushroom or vegetable stock (add a little soy for umami).
Serve piping hot, and warn everyone the bowls are molten. It’s a slow-Sunday kind of soup — cheap, patient, and deeply satisfying on the coldest nights.
Frequently asked questions
How long does it really take to caramelize the onions?
Longer than most recipes admit — a proper deep caramelization takes at least 45 minutes, often closer to an hour, over medium-low heat. There's no true shortcut; rushing on high heat burns them instead of caramelizing them. Be patient, stir regularly, and let them go from soft to golden to deep mahogany and jammy. That colour is the entire flavour of the soup.
What's the best cheese and bread for the top?
Gruyère is classic — it melts beautifully and has a nutty, savoury flavour. Comté, Emmental, or a good Swiss also work. For the bread, use a sturdy baguette or country loaf, sliced and toasted so it holds up under the broiler without turning to mush. Toast it first, float it on the soup, pile on the cheese, and broil.
Can I make it without an oven-safe bowl?
Yes. If you don't have broiler-safe bowls, make the cheese toasts separately: toast baguette slices, top with Gruyère, and broil them on a tray until melted and bubbling, then float one on each bowl of soup. You get the same result without needing oven-proof crocks.