Soupe à l'Oignon Gratinée
A classic French onion soup featuring deeply caramelized onions simmered in a rich beef broth, topped with toasted baguette slices and a generous layer of melted, bubbly Gruyère cheese. A comforting and iconic Parisian bistro dish.
🧂 Ingredients
- 1.5 kg Yellow onions(About 6-8 medium onions. Slice thinly.)
- 60 g Unsalted butter
- 15 ml Olive oil(Optional, to help prevent butter from burning.)
- 1.5 L Beef stock(Good quality, low-sodium is preferred.)
- 200 ml Dry white wine(Such as Sauvignon Blanc or Pinot Grigio. Can substitute with dry sherry.)
- 200 g Gruyère cheese(Grated. Can substitute with Emmental or Comté.)
- 1 Baguette(Stale or day-old baguette, sliced into 1-inch thick rounds.)
- 3 sprigs Fresh thyme(Or 1 teaspoon dried thyme.)
- 1 Bay leaf
- Salt(To taste.)
- Black pepper(Freshly ground, to taste.)
👨🍳 Instructions
- 1
Prepare the onions: Peel and thinly slice the yellow onions. Aim for consistent thickness for even caramelization.
⏱️ 10 minutes - 2
Caramelize the onions: Melt the butter (and olive oil, if using) in a large, heavy-bottomed pot or Dutch oven over medium-low heat. Add the sliced onions and a pinch of salt. Cook, stirring occasionally, for 60-75 minutes, or until the onions are deeply golden brown, soft, and sweet. This slow caramelization is crucial for flavor development. Adjust heat as needed to prevent burning; if onions start to stick or brown too quickly, reduce heat and stir more frequently.
⏱️ 60-75 minutes - 3
Deglaze and add liquids: Increase the heat to medium-high. Pour in the white wine and scrape the bottom of the pot to loosen any browned bits (fond). Let the wine bubble and reduce by about half, about 3-5 minutes.
⏱️ 5 minutes - 4
Simmer the soup: Pour in the beef stock. Add the fresh thyme sprigs (or dried thyme) and the bay leaf. Bring the soup to a gentle simmer, then reduce the heat to low, cover partially, and let it simmer for at least 30 minutes to allow the flavors to meld. Season with salt and freshly ground black pepper to taste.
⏱️ 30 minutes - 5
Prepare the bread: While the soup simmers, toast the baguette slices until lightly golden and crisp. You can do this in a toaster, under the broiler, or in a dry skillet.
⏱️ 5-10 minutes - 6
Assemble and gratinée: Preheat your broiler. Remove the thyme sprigs and bay leaf from the soup. Ladle the hot soup into individual oven-safe bowls. Place 2-3 toasted baguette slices on top of the soup in each bowl. Generously cover the bread with grated Gruyère cheese, ensuring it extends slightly over the rim of the bowl.
⏱️ 5 minutes - 7
Broil until golden: Carefully place the bowls on a baking sheet (for easier handling and to catch drips). Place the baking sheet under the preheated broiler. Broil for 2-4 minutes, watching very closely, until the cheese is melted, bubbly, and beautifully golden brown. Be careful not to burn the cheese.
⏱️ 2-4 minutes - 8
Serve immediately: Carefully remove the bowls from the oven using oven mitts. Let them rest for a minute before serving, as they will be extremely hot.
⏱️ 1 minute
💡 Pro Tips
- ✓Patience is key for caramelizing onions; low and slow heat develops the best flavor and sweetness.
- ✓Stir the onions frequently during caramelization, especially towards the end, to prevent them from burning and ensure even browning.
- ✓Use good quality beef stock for a richer, more flavorful soup base.
- ✓Ensure your bowls are oven-safe and broiler-safe. Place them on a baking sheet for stability and to catch any spills.
- ✓Watch the cheese closely under the broiler; it can go from perfectly golden to burnt very quickly.
✨ Twist Ideas
Inspiration for your own version of this recipe
- For a vegetarian version, use a rich vegetable stock and consider adding a splash of soy sauce or mushroom powder for umami.
- Substitute dry sherry for white wine for a slightly different flavor profile.
- Experiment with different cheeses like Emmental, Comté, or even a mix of cheeses.
- Add a splash of brandy or cognac to the soup along with the wine for extra depth.