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The Ultimate French Onion Soup Recipe

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★★★★★

4.8 from 71 reviews

This Ultimate French Onion Soup recipe combines deeply caramelized onions with a rich homemade beef stock, finished with toasted baguette slices and melted Gruyere cheese for a classic, comforting French dish.

Ingredients

Scale

Beef Stock

  • 2 1/2 lbs beef finger ribs
  • 1/2 onion, chopped
  • 2 large carrots, chopped
  • 2 celery ribs, chopped
  • 4 garlic cloves, smashed
  • 2 fresh bay leaves
  • 20 cups water

French Onion Soup

  • 4 tablespoons unsalted butter
  • 3 white onions
  • 3 yellow onions
  • 3 garlic cloves, thinly sliced
  • 2 fresh bay leaves
  • 1 tablespoon fresh thyme leaves
  • 2 teaspoons Dijon mustard
  • 1 tablespoon Worcestershire sauce
  • 2/3 cup dry vermouth
  • 8 cups beef stock (from above)
  • Kosher salt, to taste
  • Freshly cracked black pepper, to taste

For the Croutons & Topping

  • 1/2 French baguette, sliced 1 inch thick
  • 3 tablespoons softened butter
  • 1 garlic clove (for rubbing on toasted bread)
  • 1 1/2 cups shredded Gruyere cheese

Instructions

  1. Roast the beef bones: Preheat your oven’s broiler and line a baking sheet with foil. Arrange the beef finger ribs in a single layer and place under the broiler on the top rack for 12-15 minutes, flipping halfway, until deeply browned. This roasting adds rich flavor to the stock.
  2. Prepare the beef stock: Transfer the roasted ribs and any collected juices into a large stock pot. Add chopped onion, carrots, celery, smashed garlic, bay leaves, and 20 cups water. Bring to a simmer over medium heat, skimming off any foam that surfaces. Continue simmering gently until the liquid reduces by just over half, yielding about 8-10 cups of rich broth. Strain the stock through a fine mesh strainer and discard solids.
  3. Slice the onions: Peel the white and yellow onions and slice them evenly into 2mm thick slices using a mandoline or a sharp knife. Set aside.
  4. Caramelize the onions: In a large Dutch oven, melt the unsalted butter over medium heat until foamy. Add the sliced onions and toss to coat. Cover and cook for 5 minutes to soften. Then uncover, reduce heat to medium-low, lightly season with kosher salt and freshly cracked black pepper, add sliced garlic and bay leaves, and cook uncovered, stirring every 5-10 minutes until onions are deeply golden and caramelized. This process takes about 45 minutes to 1 hour.
  5. Season the onions: Increase heat to medium and stir in Dijon mustard, Worcestershire sauce, and fresh thyme leaves. Once sizzling, pour in the dry vermouth and allow it to simmer for 5 minutes to deglaze the pan and develop layers of flavor.
  6. Make the soup base: Add the prepared beef stock to the caramelized onions and bring to a gentle simmer. Cook for 15-20 minutes until the soup thickens slightly. Adjust seasoning with salt and pepper to taste.
  7. Toast the bread: Preheat your oven to 425°F (220°C). Arrange the baguette slices on a baking sheet, spread each slice with softened butter, and season with salt and pepper. Toast in the oven for 7-10 minutes until golden brown. Immediately rub each toasted slice with a cut garlic clove to infuse subtle garlic flavor.
  8. Assemble and broil the soup: Ladle the hot soup into oven-safe bowls. Top each bowl with the garlic-rubbed toasted baguette slices, then cover generously with shredded Gruyere cheese. Place the bowls on a baking sheet and transfer to the oven. Bake for 10 minutes, finishing under the broiler if necessary to achieve a bubbly and golden cheese crust.

Notes

  • Use a mandoline or very sharp knife to ensure evenly sliced onions for even caramelization.
  • Caramelizing onions slowly over low heat is essential to develop the soup’s signature deep flavor and sweetness.
  • Homemade beef stock adds richness, but high-quality store-bought beef broth can be used for convenience.
  • Dry vermouth adds subtle complexity; if unavailable, a dry white wine or sherry can be substituted.
  • Be cautious broiling the cheese to avoid burning; watch closely during the last few minutes.
  • Leftover soup and toasted baguette slices can be refrigerated separately and assembled fresh before serving.

Keywords: French Onion Soup, Classic French Soup, Caramelized Onion Soup, Gruyere Cheese Soup, Beef Stock Soup

Find it online: https://heutigemahlzeiten.com/the-ultimate-french-onion-soup-recipe/