Years ago I worked in New York City a block from Les Halles, the restaurant Anthony Bourdain was associated with for most of his career before it closed in 2017. The first time I ate there I ordered the French onion soup and a sandwich. I genuinely could not tell you what was on that sandwich. I have never forgotten that soup.

This recipe is my take on the Les Halles version, simplified in a few places to make it more approachable for a home kitchen, but it keeps everything that made the original memorable. There is no shortcut for the onions here. You let them go low and slow until they are deeply caramelized, and that is what carries the entire dish.

Check out the video below to see the full process.

The Onions Are Everything

This soup lives and dies on how well you caramelize the onions. There is no chicken stock, beef broth, wine, or cheese that can save a batch of onions that got rushed or burned. Plan for 30 to 45 minutes of mostly hands-on time at the stove, stirring often over medium-low heat.

You are looking for a deep medium brown color, not the pale golden color you would use for most other dishes. The sugars in the onions need real time to break down and develop. If you smell anything bitter or see dark, crusty bits forming unevenly, you have gone too far and too fast. Drop the heat and add a splash of water to loosen things up if that happens.

Building the Broth

Once the onions are caramelized, the wine goes in to deglaze the pot and pick up everything that has built up on the bottom. A couple minutes is all it needs before the balsamic vinegar goes in, followed by the broth. From there it is mostly hands-off — let it simmer for 45 minutes to an hour so the flavors have time to come together.

I use dark chicken stock or a quality beef broth here. Either works well. The deeper and more flavorful your base, the better the final soup is going to be, so do not reach for the thinnest broth on the shelf.

The Bouquet Garni

This is a small bundle of fresh thyme, parsley, and a bay leaf that simmers in the soup to add a layer of herbal flavor without overpowering the onions. Tie the herbs together with kitchen twine or just drop them in loose and fish them out before serving. Either way works.

Making the Crocks

This is the part that turns a good bowl of soup into the version everyone is picturing when they think of French onion soup. Ladle the soup into oven-safe crocks, lay a couple of baguette toasts on top, and pile on a generous amount of grated gruyere.

From there you have two options. A broiler will melt and brown the cheese in just a couple minutes — keep a close eye on it because the line between perfectly browned and burnt happens fast under a broiler. If you have a kitchen torch, that gives you more control and lets you get an even, bubbly brown across the whole top without risking the rest of the crock.

A Note on the Toasts

Cut the baguette on a bias for more surface area, around half an inch thick. A light drizzle of olive oil and a trip in the oven until both sides are browned is all they need. You want them sturdy enough to hold up under the broiler without turning to mush once they hit the soup.