French onion soup

Prep Time: 20 minutes | Cook Time: 1 hour 15 minutes | Total Time: 1 hour 35 minutes
Intensity: Medium (Requires patient caramelization)
Yield: 4-6 generous servings
Lasts: Refrigerates well for up to 4 days. Soup base freezes beautifully for up to 3 months (add fresh bread and cheese when serving).

There are few dishes as deeply comforting and universally adored as a well-made French Onion Soup. This recipe is a celebration of simple ingredients transformed through time and patience into something extraordinary. Sweet, slow-caramelized onions are simmered in a rich, herb-infused beef broth, then crowned with a crusty baguette slice and a cap of bubbly, golden Gruyère cheese. It’s a symphony of savory, sweet, and umami flavors in every spoonful. While the process requires some attention, the result is a restaurant-quality soup that is well worth the effort.

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Ingredients

For the Soup:

• 3 lbs (about 5-6 large) yellow onions, thinly sliced

• 4 tbsp unsalted butter

• 2 tbsp olive oil

• 1 tsp granulated sugar

• 2 cloves garlic, minced

• 1/2 cup dry white wine (like Sauvignon Blanc) or dry vermouth

• 8 cups good-quality beef broth (low-sodium preferred)

• 2 cups water

• 2 bay leaves

• 4-5 sprigs fresh thyme (or 1 tsp dried)

• 1 tsp kosher salt, plus more to taste

• 1/2 tsp freshly ground black pepper

For the Assembly:

• 1 baguette, cut into 1-inch thick slices

• 1 1/2 cups freshly grated Gruyère cheese

• 1/2 cup freshly grated Parmesan cheese (optional)

Special Equipment:

• Large, heavy-bottomed pot or Dutch oven (5-7 quart)

• Soup crocks or oven-safe bowls

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Instructions

Step 1: Caramelize the Onions (The Heart of the Soup)

1. In your large heavy-bottomed pot or Dutch oven, melt the butter and olive oil over medium-low heat.

2. Add all the sliced onions and stir to coat them in the fat. Cover the pot and let the onions “sweat” for 15 minutes, stirring once or twice. This draws out their moisture.

3. Uncover, increase the heat to medium, and stir in the sugar and 1 tsp of salt. Cook, stirring frequently, for 30-45 minutes. This is where the magic happens. Be patient. The onions will first soften, then turn translucent, then gradually deepen to a golden, then a rich, nutty brown. Scrape the bottom of the pot to prevent burning. The goal is an even, deep caramelization—this is non-negotiable for the soup’s signature flavor.

Step 2: Build the Broth

1. Once the onions are a deep golden brown, add the minced garlic and cook for 1 minute until fragrant.

2. Pour in the white wine to deglaze the pot, scraping up any delicious browned bits (the fond) from the bottom. Let it simmer until the wine is mostly evaporated, about 3-4 minutes.

3. Add the beef broth, water, bay leaves, and thyme. Bring to a boil, then reduce heat to a low simmer.

4. Partially cover and let the soup simmer gently for at least 30 minutes (45 is better) to allow the flavors to fully meld. Season with additional salt and pepper to taste. Discard the bay leaves and thyme sprigs.

Step 3: Prepare the Topping

1. While the soup simmers, preheat your oven to 400°F (200°C). Arrange the baguette slices on a baking sheet and toast in the oven for 5-7 minutes per side, until crisp and dry. Set aside. Reduce oven temperature to 350°F (175°C) for final broiling.

Step 4: Assemble and Broil

1. Ladle the hot soup into oven-safe crocks or bowls placed on a sturdy baking sheet.

2. Place 1-2 toasted baguette slices on top of the soup in each bowl, pressing down slightly so it absorbs some broth.

3. Generously pile the grated Gruyère (and Parmesan, if using) over the bread, covering it completely and allowing some cheese to spill over onto the soup’s surface.

4. Carefully place the baking sheet in the oven and broil on a high rack for 3-5 minutes, watching closely, until the cheese is completely melted, bubbly, and beautifully browned in spots.

5. Let cool for 5 minutes—the soup and cheese will be molten hot.

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Serving & Storing Notes

Serving: Serve immediately, with a warning about the hot bowls! A simple green salad with a vinaigrette is the perfect accompaniment to cut through the richness.

Storing & Reheating:

• Refrigerator: Store cooled soup (without bread or cheese) in an airtight container for up to 4 days.

• Freezer: The soup base freezes exceptionally well for up to 3 months. Thaw overnight in the refrigerator before reheating and assembling.

• To Reheat: Warm the soup base in a pot over medium heat until simmering. Proceed with assembly and broiling steps.

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Nutrition Information

(Per serving, based on 6 servings, including one baguette slice and Gruyère cheese topping)

*Percent Daily Values are based on a 2000 calorie diet.
**Sodium content is highly dependent on the broth used. Using low-sodium broth and salting to taste is recommended for better control.

Enjoy this timeless classic, a true testament to the power of slow cooking and simple, quality ingredients.