Traditional French Onion Soup (Soupe à l'oignon gratinée)

• •3 lb yellow onions, peeled and thinly sliced
• •3 tablespoon unsalted butter
• •1 tablespoon olive oil
• •1 teaspoon granulated sugar
• •1 teaspoon salt
• •0.5 teaspoon freshly ground black pepper
• •1 tablespoon all-purpose flour
• •0.5 cup dry white wine (such as Sauvignon Blanc or dry sherry)
• •6 cup beef broth, high quality, low sodium
• •1 bay leaf
• •3 fresh thyme sprigs
• •8 slices day-old baguette, sliced 1-inch thick
• •6 oz Gruyère cheese, grated

Instructions

1. 1

   In a large, heavy-bottomed pot or Dutch oven, melt the unsalted butter and olive oil over medium-low heat. Add the thinly sliced onions, granulated sugar (if using), 1 teaspoon of salt, and 0.5 teaspoon of freshly ground black pepper.

2. 2

   Cook the onions slowly, stirring frequently, for 45-60 minutes, or until they are deeply caramelized to a rich, golden-brown color. This process requires patience; do not rush it. If the onions start to stick to the bottom, add a tablespoon of water or broth to deglaze the pot and scrape up any browned bits.

3. 3

   Sprinkle the all-purpose flour over the caramelized onions and stir continuously for 1-2 minutes to cook out the raw flour taste.

4. 4

   Pour in the dry white wine or dry sherry. Scrape the bottom of the pot with a wooden spoon to deglaze thoroughly, loosening any remaining browned bits. Cook for 2-3 minutes until the wine has mostly evaporated.

5. 5

   Add the beef broth, bay leaf, and fresh thyme sprigs to the pot. Bring the soup to a gentle simmer, then reduce the heat to low, cover partially, and let it cook for at least 20-30 minutes to allow the flavors to meld. Taste and adjust seasoning with additional salt and pepper as needed. Remove the bay leaf and thyme sprigs before serving.

6. 6

   While the soup simmers, preheat your oven broiler. Arrange the baguette slices on a baking sheet and toast lightly under the broiler until golden on both sides. Watch them closely to prevent burning.

7. 7

   Ladle the hot French onion soup into individual oven-safe bowls. Place 2 toasted baguette slices on top of the soup in each bowl.

8. 8

   Generously sprinkle the grated Gruyère cheese over the baguette slices, ensuring the cheese covers the bread and slightly overlaps the rim of the bowl.

9. 9

   Place the bowls on a baking sheet (for easier handling and to catch any drips) and broil for 2-5 minutes, watching very carefully, until the cheese is melted, bubbly, and deeply golden brown. It can go from perfect to burnt quickly.

10. 10

    Serve immediately, being extremely careful as the bowls and their contents will be very hot.

Chef's Tips

• 💡Patience is Key: The slow caramelization of the onions is the absolute heart of this soup. Do not rush this step; low and slow heat is crucial for developing the deep, rich flavor without burning the onions.
• 💡Quality Broth Matters: A high-quality beef broth or homemade beef stock will make a significant difference in the final taste of your soup. Avoid thin, watery broths.
• 💡Choose the Right Cheese: Gruyère is the traditional choice for its nutty flavor and excellent melting properties, creating that perfect golden crust. Comté or Emmental are good substitutes if Gruyère is unavailable.
• 💡Oven-Safe Bowls: Always ensure your serving bowls are oven and broiler-safe to prevent cracking. Placing them on a baking sheet also makes them easier and safer to transfer in and out of the hot oven.
• 💡Watch the Broiler Closely: Broilers are powerful and can quickly burn the cheese. Keep a constant eye on the soup during the gratinéing step to achieve a beautiful, bubbly, golden-brown crust without overcooking.