Did you know that French onion soup, often a staple in restaurants, actually originated as a humble peasant soup made with just onions, stale bread, and water? Today’s versions might be a bit fancier, but this soup is still wonderfully simple to make at home. The key is patience. The onions need to be cooked low and slow so that they sweeten and turn a rich brown caramel color without burning. In addition to giving the onions the proper time and attention, I add a bit of sugar to enhance the sweetness of the onions, and I also stir in a bit of flour to add body to the broth—two tricks I picked up working in a French restaurant that made the best French onion soup ever. Finally, to add even more flavor, I top the croutons with two types of cheese.
What You’ll Need to Make French Onion Soup
How To Make French Onion Soup
To begin, in a large Dutch oven or soup pot, melt the butter over medium heat. Add the oil, onions, salt, pepper, and sugar.
Cook, stirring occasionally, until the onions are deep golden brown and caramelized, 45 to 55 minutes.
In the beginning, you will only need to stir the onions occasionally. As they start to brown midway through cooking, you’ll need to stir them more frequently. Also, be sure to scrape the fond (or brown particles) from the bottom of the pan.
Add the wine and raise the heat to high.
Cook, stirring with a wooden spoon to scrape any fond from the bottom of the pan, until almost all of the liquid has evaporated and the onions are jammy, 8 to 10 minutes.
Add the flour.
Cook for about one minute to dissolve the flour.
Add the broth, Worcestershire sauce, thyme, and bay leaves to the pot.
Bring to a boil, reduce the heat to a simmer, and cook, covered, for about 30 minutes. Add the sherry, then taste and adjust seasoning if necessary. If the soup needs a deeper flavor, try a few shakes of Worcestershire sauce. If it’s not quite sweet enough, add 1/4 teaspoon sugar.
While the soup simmers, preheat the oven to 400 F and set an oven rack in the middle position. Arrange the baguette slices in a single layer on a baking sheet.
Bake until the bread is dry, crisp, and golden at edges, about 10 minutes. Set aside.
Adjust an oven rack 6 inches from broiler element and heat broiler. Set individual broiler-safe crocks on a baking sheet and divide the hot soup among the crocks. Be sure the soup is very hot as it won’t warm up much in the oven. Top each crock with 1 or 2 baguette slices (do not overlap slices).
Sprinkle evenly with Gruyère and then Parmigiano Reggiano.
Slide the crocks into the oven and broil until the cheese is melted and bubbly around edges, 3 to 5 minutes. (Alternatively, if using regular soup bowls: Top each toast slice with some cheese and return to broiler to melt, about 2 minutes more. Divide the soup among bowls and top each serving with two cheese toasts.)
French Onion Soup
Servings: 4 to 6 Prep Time: 20 Minutes Cook Time: 1 Hour 40 Minutes Total Time: 2 Hours- 4 tablespoons unsalted butter
- 1 tablespoon vegetable oil
- 3 pounds Vidalia (or sweet) onions (about 5 medium), halved lengthwise and thinly sliced
- ¾ teaspoon salt
- ½ teaspoon freshly ground black pepper
- ¾ teaspoon granulated sugar
- 1 cup dry white wine
- 2 tablespoons all-purpose flour
- 6 cups beef broth
- 1 teaspoon Worcestershire sauce
- ½ teaspoon dried thyme
- 2 bay leaves
- 1 small baguette, cut into ½-in slices
- 1 tablespoon dry sherry
- 8 ounces Gruyère cheese, grated (about 2 heaping cups; look for one imported from Switzerland)
- ½ cup grated Parmigiano Reggiano
In a large Dutch oven or soup pot, melt the butter over medium heat. Add the oil, onions, salt, pepper, and sugar. Cook, uncovered, stirring occasionally with a wooden spoon, until onions are deep golden brown and caramelized, 45 to 55 minutes. In the beginning, you will only need to stir the onions occasionally. As they start to brown midway through cooking, you will need to stir them frequently, scraping the fond (the brown particles) from the bottom of the pan. If the onions are browning too quickly, reduce the heat slightly or add a few tablespoons of water to deglaze the pan and continue cooking.
Add the wine and raise the heat to high. Cook, stirring with a wooden spoon to scrape any fond from the bottom of the pan, until almost all of the liquid has evaporated and the onions are jammy, 8 to 10 minutes.
Add the flour and cook, stirring constantly, for one minute.
Add the broth, Worcestershire sauce, thyme, and bay leaves to the pot. Bring to a boil, reduce the heat to a simmer, and cook, covered, for about 30 minutes.
While the soup simmers, preheat the oven to 400 F and set an oven rack in the middle position. Arrange the baguette slices in a single layer on a baking sheet and bake until the bread is dry, crisp, and golden at edges, about 10 minutes. Set aside.
When the soup is finished, remove the bay leaves and add the sherry; taste and adjust seasoning if necessary. If the soup needs a deeper flavor, try a few shakes of Worcestershire sauce. If it’s not quite sweet enough, add ¼ teaspoon sugar.
Adjust an oven rack 6 inches from broiler element and heat broiler. Set individual broiler-safe crocks on a baking sheet and divide the hot soup among the crocks (be sure the soup is very hot as it won’t warm up much in the oven). Top each crock with 1 or 2 baguette slices (do not overlap slices) and sprinkle evenly with Gruyère and then Parmigianno Reggiano. Slide the crocks into the oven and broil until the cheese is melted and bubbly around edges, 3 to 5 minutes. Let the crocks cool for a few minutes before serving. (Alternatively, if using regular soup bowls: Top each toast slice with some cheese and return to broiler to melt, about 2 minutes more. Divide the soup among bowls and top each serving with two cheese toasts.)
Make-Ahead Instructions: The soup can be made and refrigerated up to 3 days ahead (without toasts or cheese), or up to 3 months ahead and frozen. Toasts can be made (without the cheese) and kept sealed at room temperature for up to 3 days.
Nutrition Information
Per serving (5 servings)
Calories: 642, Fat: 31 g, Saturated fat: 17 g, Carbohydrates: 53 g, Sugar: 19 g, Fiber: 4 g, Protein: 31 g, Sodium: 1,697 mg, Cholesterol: 82 mg
