How to Make French Onion Soup (Classic Caramelized Recipe)

Pull everything out and lay it on the counter before you start. You will need 4 pounds of yellow onions, 8 cups of low-sodium beef stock, a small baguette, 1 1/2 cups of Gruyere cheese, 4 tablespoons of butter, olive oil, a half cup of dry vermouth (or a cup of dry white wine), 4 cloves of garlic, 1 tablespoon of all-purpose flour, 2 tablespoons of tomato paste, fresh thyme, kosher salt, and black pepper.

Beef stock is doing most of the heavy lifting in this soup, so use the best you can find. Homemade is ideal. Otherwise a good-quality low-sodium store stock, or a concentrated paste like Better Than Bouillon mixed to label strength, will work well.

Slice the onions thinly from root to stem. Aim for uniform slices, around an eighth of an inch thick, so they soften and caramelize at the same rate. Buy the largest yellow onions you can find. Working through 30 small onions is a chore. A handful of big ones gets you to 4 pounds in just a few minutes.

Pile the sliced onions in your biggest bowl. They will look like a mountain. That is the whole point - they cook down to roughly a quarter of their starting volume by the time they are properly caramelized.

Heat an 8-quart Dutch oven over medium. A wide 14-inch pan works even better because the onions caramelize faster. Add 2 tablespoons of olive oil, then dump in all the onions. Sprinkle 1 teaspoon of salt and pour in a couple of ounces of water.

Stir to coat everything, then cover the pot and let it ride for about 12 minutes. The lid traps steam and gives the onions a head start - they collapse and release their own water without much attention from you. The salt pulls more water out and seasons them from the inside.

Pull the lid off and add 4 tablespoons of butter. From here on, the onions need attention. Stir more often with a flat-edge wooden spoon and adjust the heat down whenever you see browning happening too fast. If the pan starts to scorch, splash in a tablespoon of water - it evaporates in seconds and resets the bottom of the pot without changing the cook.

Keep going. Around the 30-minute mark the onions look light brown. At 45 minutes they should be a deep, rich caramel color and the volume in the pan is about a quarter of what you started with. That is the make-or-break stage of this soup. Cranking up the heat to rush it will give you bitter, burnt onions instead of sweet ones.

With the onions caramelized, add 4 cloves of minced garlic and stir for a minute until fragrant. Add 2 tablespoons of tomato paste and mix it through the onions. Cook the paste for about 4 minutes, stirring often, until it turns a shade darker. That short toast in the pan deepens its flavor and gets rid of the raw can-of-tomato edge.

If anything starts to stick or scorch in this stage, a splash of water is still your friend. The flavors are concentrating fast at this point, so taste the onions and adjust salt with a light hand.

Sprinkle 1 tablespoon of all-purpose flour over the onions and stir constantly for about 2 minutes. You want to cook out the raw flour taste and let the flour absorb the butter and onion fat. The mixture goes from chalky white to a uniform, glossy paste coating every onion strand.

This is a quick onion-based roux - the same roux concept used to thicken gumbos, gravies, and beechamel - just built directly into the dish. It is what gives French onion soup that slightly thickened, silky body instead of plain broth.

Pour in 1/2 cup of dry vermouth (or 1 cup of dry white wine) and scrape the bottom of the pot to lift any browned bits. The wine reduces almost instantly with the heat where it is. You do not need to cook it down separately.

Add 8 cups of low-sodium beef stock and 1 tablespoon of fresh thyme leaves. Whisk to break up any lumps from the roux, then bring everything to a gentle boil and drop the heat to a low simmer. Cook for 15 to 20 minutes to marry the flavors. Taste, then season with salt and plenty of black pepper. If you have an extra hour, let the pot cool and refrigerate overnight - this soup is twice as good the next day.

While the soup simmers, slice the baguette into rounds about a half inch thick. Two or three rounds per bowl is usually enough to cover the top. Cubing the bread into smaller pieces also works if you prefer crouton-style chunks instead of full slices.

Shred 1 1/2 cups of Gruyere on the large holes of a box grater, or slice it thin if you have a wedge. Set the broiler to high and position the rack so an oven-safe bowl with cheese on top will sit a few inches under the element.

Set your oven-safe crocks on a baking sheet. The sheet catches drips and makes it easy to slide everything in and out of the oven. Ladle the hot soup into each bowl, then float two slices of baguette across the top.

Pile shredded Gruyere over the bread. Cover most of the bread but leave a small edge poking out - that gets crusty under the broiler and gives you a little contrast against the gooey cheese. Do not skimp on the cheese. This is the moment to be generous.

Slide the bowls under the broiler. Watch them the whole time - the cheese can go from gold to scorched in under a minute. Pull them out at 2 to 4 minutes, when the Gruyere is bubbling, melted through, and has spots of golden brown around the edges.

Let the bowls sit on the counter for a couple of minutes before serving so the soup is hot but not lava-mouth hot. Garnish with a few fresh thyme leaves. Set the bowl on a plate to catch dribbles and serve right away.