Description
Classic French Onion Soup (Soupe à l’Oignon Gratinée) features deeply caramelized onions simmered in a rich chicken stock and dry sherry broth, topped with toasted rustic bread and melted Gruyère cheese. This comforting, savory soup is finished under the broiler for a golden, bubbly cheese crust and garnished with fresh chives, perfect for a cozy meal.
Ingredients
Scale
Soup Base
- 6 tablespoons (90g) unsalted butter, plus more for bread
- 3 pounds (1.4kg) yellow or mixed onions, sliced 1/8 inch thick
- Kosher salt and freshly ground black pepper
- 1/2 cup (120ml) dry sherry (such as Amontillado)
- 2 quarts (1.8L) homemade or store-bought low-sodium chicken stock
- 2 sprigs thyme
- 1 bay leaf
- 1 teaspoon (5ml) Asian fish sauce (optional)
- 1 teaspoon (5ml) cider vinegar
For Serving
- 8 bowl-size slices rustic bread, toasted until crisp
- 1 medium clove garlic
- 1 pound (450g) Gruyère cheese, grated
- Freshly minced chives, for garnish
Instructions
- Caramelize the Onions: In a large stainless steel saucepan or two large skillets, melt butter over medium-high heat until foaming. Add the sliced onions and cook, stirring occasionally, until softened, about 8 minutes. Reduce heat to medium-low and continue cooking, stirring frequently to prevent sticking or burning, until onions become very sweet, deeply caramelized, and golden-brown in color, about 1 to 2 hours. If onions start to stick or burn, add 1 tablespoon of water to deglaze and continue cooking. Season with kosher salt and freshly ground black pepper to taste.
- Deglaze with Sherry: Add dry sherry to the caramelized onions and bring to a simmer, scraping up any browned bits from the pan bottom to enhance flavor. If using two skillets, divide the sherry between them, then transfer all onions and liquid into one pot or Dutch oven to continue cooking. Simmer until the alcohol aroma mostly dissipates, about 3 minutes.
- Add Stock and Simmer: Stir in the chicken stock, thyme sprigs, and bay leaf. Increase heat to medium-high and bring to a simmer. Once simmering, reduce heat to maintain a gentle simmer and cook uncovered for 20 minutes to meld flavors.
- Finish the Soup Base: Remove and discard the thyme sprigs and bay leaf. Stir in Asian fish sauce if using, along with cider vinegar. Taste and adjust seasoning with additional salt and pepper as needed.
- Prepare the Bread and Cheese: Preheat your oven broiler and position the rack at the top. Butter the toasted bread slices lightly and rub each with the halved garlic clove to infuse flavor.
- Assemble and Broil: Spoon a small amount of the hot broth into the bottom of four ovenproof serving bowls. Top each with half of the toasted bread slices. Sprinkle grated Gruyère cheese over the toasts, then ladle more soup and onions over, filling the bowls nearly to the top. Add the remaining toasted bread slices, pressing them gently into the soup so they are partially submerged. Cover the tops generously with the remaining Gruyère cheese. Place the bowls on a rimmed baking sheet and broil until the cheese is melted, bubbly, and browned in spots, about 3–5 minutes depending on your broiler.
- Garnish and Serve: Remove soup from the oven, sprinkle with freshly minced chives for a mild oniony freshness, and serve immediately while hot and deliciously cheesy.
Notes
- Slice the onions uniformly about 1/8 inch thick for even caramelization.
- Use a heavy-bottomed pan such as stainless steel or cast iron to develop the best fond and prevent burning.
- Sherry adds depth and complexity; substitute dry white wine if unavailable.
- Low-sodium chicken stock helps control overall saltiness, adjusting seasoning at the end.
- Toasting the bread adds a sturdy base that prevents sogginess when submerged in soup.
- Gruyère cheese melts beautifully and offers the classic flavor, but Emmental or Comté can be used as alternatives.
- Broiling the assembled soup is essential to get the signature gratinée crust on the cheese topping.
Nutrition
- Serving Size: 1 bowl (approximately 1/4 recipe)
- Calories: 1000 kcal
- Sugar: 21 g
- Sodium: 2653 mg
- Fat: 57 g
- Saturated Fat: 33 g
- Unsaturated Fat: 24 g
- Trans Fat: 0 g
- Carbohydrates: 72 g
- Fiber: 6 g
- Protein: 52 g
- Cholesterol: 172 mg
