📝 About This Recipe
A deep, mahogany-hued masterpiece that honors the bistro traditions of Paris while remaining completely gluten-free. This soul-warming soup relies on the patient caramelization of five pounds of onions, deglazed with a touch of dry sherry to create a complex, silky broth. Topped with hand-toasted gluten-free baguette rounds and a bubbling, golden blanket of aged Gruyère, it is the ultimate comfort dish for those who refuse to compromise on flavor or texture.
🥗 Ingredients
The Onion Base
- 5 pounds Yellow Onions (peeled and thinly sliced pole-to-pole)
- 4 tablespoons Unsalted Butter (high-quality European style preferred)
- 1 tablespoon Extra Virgin Olive Oil
- 1/2 teaspoon Granulated Sugar (to assist in caramelization)
- 1 teaspoon Kosher Salt (plus more to taste)
The Broth & Aromatics
- 1/2 cup Dry Sherry (or dry white wine)
- 8 cups Beef Bone Broth (ensure certified gluten-free)
- 4-5 pieces Fresh Thyme Sprigs (tied with kitchen twine)
- 1 piece Bay Leaf (dried)
- 2 tablespoons Gluten-Free Flour (all-purpose blend)
- 1/2 teaspoon Black Pepper (freshly cracked)
The GF Crostini & Topping
- 1 loaf Gluten-Free Baguette (sliced into 1-inch thick rounds)
- 1 piece Garlic Clove (halved)
- 2 cups Gruyère Cheese (freshly grated)
- 1/4 cup Parmesan Cheese (finely grated)
👨🍳 Instructions
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1
In a large, heavy-bottomed Dutch oven, melt the butter and olive oil over medium-low heat. Add the sliced onions and toss to coat thoroughly.
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2
Cover the pot and cook for 15 minutes. The onions will soften and release their moisture. Stir occasionally to ensure even cooking.
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3
Remove the lid, increase the heat to medium, and stir in the salt and sugar. This is where the magic happens; cook the onions for 45-60 minutes, stirring every 5-10 minutes.
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4
As the onions begin to stick to the bottom, use a wooden spoon to scrape up the brown bits (the fond). If they brown too quickly, add a tablespoon of water. The goal is a deep, uniform jam-like consistency and chocolate-brown color.
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5
Sprinkle the gluten-free flour over the caramelized onions and stir for 2 minutes to cook out the raw flour taste.
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6
Pour in the dry sherry to deglaze the pot, scraping up every last bit of flavor from the bottom. Let the liquid reduce by half.
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7
Slowly pour in the beef bone broth. Add the thyme bundle and the bay leaf. Bring to a simmer, then reduce heat to low.
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8
Simmer the soup partially covered for 30 minutes, allowing the flavors to meld and deepen. Remove the thyme and bay leaf when finished.
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9
While the soup simmers, preheat your oven to 400°F (200°C). Place the gluten-free baguette slices on a baking sheet and toast for 5-7 minutes until crisp. Rub the warm bread with the cut side of the garlic clove.
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10
Taste the soup and adjust seasoning with additional salt and freshly cracked black pepper as needed.
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11
Switch your oven to the broiler setting. Arrange oven-safe soup crocks on a sturdy baking sheet.
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12
Ladle the hot soup into the crocks, leaving about an inch of space at the top. Place 1-2 GF crostini on top of each bowl so they float.
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13
Generously pile the grated Gruyère and Parmesan over the bread, allowing some to spill over the edges for that classic bistro look.
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14
Broil for 3-5 minutes, watching closely, until the cheese is bubbling and has developed dark brown spots. Serve immediately on saucers to protect your table from the heat.
💡 Chef's Tips
Patience is your best ingredient; do not rush the onions or they will be bitter rather than sweet. Always use a high-quality, gluten-free beef bone broth, as the liquid reduction intensifies the saltiness and flavor. If you don't have oven-safe crocks, melt the cheese on the crostini in the oven first and then float them on the soup bowls. For an extra layer of flavor, add a teaspoon of balsamic vinegar at the very end of the simmering process. Ensure your Gruyère is freshly grated from a block; pre-shredded cheeses often contain anti-caking starches that prevent a perfect melt.
🍽️ Serving Suggestions
Pair with a crisp, dry French white wine like Sancerre or a light-bodied Pinot Noir. Serve alongside a simple green salad with a sharp Dijon vinaigrette to cut through the richness. A side of roasted marrow bones makes this an incredibly decadent meal. For a non-alcoholic substitute for sherry, use 2 tablespoons of balsamic vinegar mixed with a little extra broth.