French Onion Soup

French Onion Soup is a testament to the art of French cuisine, offering a warm blend of flavors that are deeply satisfying and unforgettable. Each spoonful is a rich balance of sweet, savory, and slightly smoky notes, making it a soul-warming delight that combines flavor and comfort in one bowl

Best Onions for French Onion Soup

When making French onion soup, the slow caramelization of the onions gives the soup its rich, sweet, and savory flavor. Yellow or white onions are excellent choices because they have the right balance of flavors and can caramelize beautifully, adding depth to the soup.

Sweet onions, such as Vidalia or Walla Walla, can also be used in combination with yellow or white onions in a small amount due to their high watery content, to add a slightly sweeter note to the soup.

Ingredients for French Onion Soup

• Onions: Four medium-sized yellow or white onions are best for slow caramelization.
• Sweet Onion: One medium sweet onion for a sweet flavor or add 1/2 tsp. of sugar.
• Olive Oil: Used for sautéing and caramelizing the onions.
• Butter: Adds richness and flavor; also helps the onions create a deep, golden color.
• Salt and Black Pepper: Add to taste. They enhance the overall flavor of the soup.
• Flour (optional): A small amount thickens the soup and creates a rich, hearty texture.
• Garlic: Minced garlic cloves for their aromatic and flavorful qualities.
• Wine: Dry white or red wine for deglazing the pan and enhancing the soup’s flavor.
• Worcestershire Sauce: Provides a balanced combination of savory, sweet, and tangy flavors.
• Beef Broth: Use good-quality and flavorful broth as it forms the savory base of the soup.
• Fresh Thyme: Either leaves or sprigs to infuse the soup with a subtle herbal and earthy flavor.
• Bay Leaf: Adds an aromatic essence and a subtle herbal note, removed before serving.
• Dry Sherry: Added at the end to deepen the soup’s flavor and provide a rich, nutty taste.
• Gruyere Cheese: Nutty and slightly sweet, it forms a cheesy crust when used as a topping.
• Baguette: Sliced or cubed, these are placed in the soup before adding the cheese.

French Onion Soup Recipe

• 4 medium-sized yellow onions (572-600g), halved and thinly sliced to ¼-inch thickness    
• 1 medium sweet onion, Vidalia (331g), halved and thinly sliced
• 1 tablespoon (15ml/14g) high-quality olive oil
• 2 tablespoons (14g) unsalted butter
• 1/2 teaspoon (2g) pink or kosher salt, to taste
• 1/4 teaspoon (0.6g) freshly ground black pepper, to taste
• 1-2 cloves garlic (3g), peeled and minced
• 1 teaspoon (8g) all-purpose flour, (optional)
• 1 teaspoon (1g) thyme leaves or 7 fresh thyme sprigs
• 1/4-1/2 cup (59ml) dry white or red wine Chardonnay or Pinot Grigio
• 4 cups (32 fl.oz./946 ml) beef broth (or vegetable broth for a vegetarian version) quality is key
• 1 teaspoon (5ml) Worcestershire sauce
• 2 medium-sized dried bay leaves (2g)
• 1 tablespoon (15 ml) sherry vinegar or balsamic vinegar
• 8 slices (1-inch thick) French bread or baguette 1.5 cups (150g) shredded Gruyere cheese (or Swiss cheese), more if preferred

Recommended Equipment

• Dutch Oven: For achieving beautiful caramelization of the onions with a kettle-like flavor.
• Bowls: Ovenproof bowls for broiling the cheese-topped toast before serving.
• Wooden Long Tongs: They are excellent, heat-resistant, and useful for stirring onions.

How to Make French Onion Soup

Preheat Dutch Oven over low heat. Once warm, increase the heat to medium and add the butter and oil.

Note: Always preheat your Dutch oven over low heat to avoid damaging the enamel and prevent cracks.

Sauté Onions: Peel and slice the onions into 1/4-inch slices, ensuring they are not thinner. They will reduce in size quite a bit. Once the butter is melted, add the onions to a pot, cover with a lid, and let them soften for 5 minutes.

Caramelization: Remove the lid, add salt and ground black pepper, and cook for about 30 minutes, stirring occasionally, until they caramelize and turn a deep golden brown. Be patient; it’s worth it.

Warm the Broth: Meanwhile, warm the beef broth in a saucepan over low heat, keeping it warm until added to the pot (Important step).

Garlic and Thyme: Once the onions are caramelized, sprinkle in the plain flour (if using), add minced garlic, and thyme leaves, sauté for 1-2 minutes until fragrant.

Deglaze the pot by pouring in the white wine and scraping up any browned bits that are stuck to the bottom of the pot. These bits add delicious flavor to the soup. Cook for 2-3 minutes until most of the liquid evaporates.

Add Broth and Bay Leaf: Carefully and slowly add the warm broth and bay leaves, Worcestershire sauce, stir, and bring it to a boil. Reduce the heat to low, cover, and simmer for about 15-20 minutes.

Taste and Adjust: Taste the soup and adjust the seasonings if needed, adding more salt or pepper to your liking.

Note: It’s important to add warm liquids, especially in larger quantities, to the pot when sautéing hot ingredients. Adding cold liquids can create a sudden temperature contrast, which may lead to thermal shock, pot cracks, or spills. It’s advised to slowly add warm, not cold liquids to the pot, allowing for a smoother transition in temperature.

Make Toasts: Meanwhile, heat the broiler. Place the baguette slices on a baking sheet, drizzle with olive oil, and toast them under the broiler until they are lightly browned, 1-2 minutes. Watch them closely to prevent burning.

Sherry: Once the soup is done, add sherry, discard the bay leaves and thyme sprigs (no need to discard thyme leaves).

To Serve: Set individual ovenproof bowls on a baking sheet, and ladle the soup into each bowl. Float a slice of toasted baguette on top of each bowl of soup.

Top with Cheese: Sprinkle a generous amount of shredded Gruyere or Swiss cheese over each slice.

Broil in the oven until the cheese is melted and bubbly, and has a nice golden brown crust, 1-2 minutes.

Alternatively, you can top slices with cheese and broil beforehand, then add them to the soup to serve.

Enjoy: Carefully remove bowls from the oven (they will be hot), and let them cool slightly before serving.

Recipe Tips for Best Results

• Patience is Key: The secret to a flavorful soup is the slow caramelization of the onions.
• Onions: Yellow or white onions caramelize beautifully and add depth of flavor.
• Broth: Use a good-quality beef broth as it forms the savory base of the soup.
• Use Real Gruyere: For the classic flavor use Gruyere cheese; it’s nutty and slightly sweet.
• Keep a close eye on the toasts while broiling; they can go from brown to burned quickly.
• A Dutch oven will caramelize your onions beautifully, with rich flavors.
• Stove Temperature: Keep medium-low heat to avoid burned onions while sautéing.

Storage & Serving

Make-Ahead: You can make the soup up to 3 days in advance. Resting it for a day or two allows the flavors to blend, making a richer, even tastier soup.

Storage: Leftover soup and toasts can be refrigerated separately in airtight containers for up to 3 days.

Reheat: Warm the soup in a saucepan over low heat, stirring until it’s heated through, or use a microwave, stirring in between 30-second intervals, until it reaches your desired temperature.

Serving Suggestions

• Light Meal: French Onion Soup is delightful on its own as an appetizer or a light meal.
• Salad: Pair it with a fresh green salad for a well-rounded lunch or dinner.
• Starter Meal: It makes an excellent starter for a formal meal.
• Bread: Serve it with a side of extra crusty bread for a hearty and comforting experience.
• Recipes: Use the soup as an ingredient or starting point for other dishes and recipes.

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