Classic Onion Soup
This is a dish that rewards the cook who doesn't rush. The onions must lose their bite and take on a jammy, dark consistency that forms the backbone of the soup.
Don't skimp on the caramelization.
If the onions are pale, the soup will be one-dimensional. Watch for the point where the pan bottom collects a dark, mahogany-colored glaze.
- Heavy-bottomed Dutch oven or thick-walled soup pot
- Wooden spoon
- Broiler-safe bowls
- Mandoline or sharp chef's knife
What goes in.
- 3 lbyellow onions, sliced pole-to-pole into 1/4 inch strips
- 4 tbspunsalted butter
- 1 tbspolive oil
- 1 tspkosher salt
- 2 clovesgarlic, minced
- 1/2 cupdry white wine or dry vermouth
- 6 cupsrich beef stock
- 2fresh thyme sprigs
- 1bay leaf
- 1/2 loafday-old baguette, cut into 1-inch thick slices
- 2 cupsGruyère cheese, grated
Developing the Fond
As the onions brown, they will release sugars that stick to the bottom of the pot. Scrape these brown bits—the fond—into the onions every time you add liquid to build the flavor density.
The method.
Caramelize the onions
Melt butter and oil in the pot over medium heat. Add onions and salt. Stir to coat. Cook, stirring occasionally, until they turn a deep, dark amber color. This will take at least 45 to 60 minutes.
Deglaze and simmer
Add minced garlic and cook for 1 minute. Pour in the wine and scrape the bottom of the pot thoroughly. Add beef stock, thyme, and bay leaf. Simmer partially covered for 30 minutes.
Toast the bread
While the soup simmers, toast the baguette slices in a 400°F oven until golden and crisp.
Assemble and broil
Ladle soup into oven-safe bowls. Place a slice of toasted baguette on top. Cover generously with grated Gruyère. Place bowls on a baking sheet under a broiler until the cheese bubbles and develops dark brown, blistered spots.
Other turns to take.
Deepened Stock
Stir in a tablespoon of balsamic vinegar or Worcestershire sauce right before adding the stock for a sharper finish.
Herb Infusion
Add a small sprig of fresh rosemary along with the thyme for a more piney, aromatic profile.
When it doesn't go to plan.
Use a mix of yellow and red onions if you want a slightly sweeter, more complex flavor profile.
If the onions look like they are drying out before they are browned, add a splash of water to loosen the pot bottom.
Make sure the bread fits the diameter of the bowl so the cheese stays on top rather than sinking to the bottom.
The ones that keep coming up.
Can I use chicken stock instead?
You can, but the result will be much lighter and lack the signature deep, meaty flavor characteristic of this dish.
Why did my soup turn out thin?
It likely needed more time to reduce. Ensure the soup simmered uncovered long enough for the liquid to concentrate.
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