Ingredients:

  • 2 tbsp olive oil (30 ml)
  • 2 tbsp unsalted butter (28g)
  • 3 large yellow onions, thinly sliced (approximately 700g or 1.5 lbs)
  • 1 tsp granulated sugar (5g)
  • 1/2 tsp sea salt, plus more to taste
  • 1/4 tsp freshly ground black pepper, plus more to taste
  • 1/4 cup dry sherry (60 ml)
  • 8 cups homemade or high-quality store-bought beef broth (1.9 liters)
  • 2 sprigs fresh thyme
  • 1 bay leaf
  • 1 tbsp Worcestershire sauce (15 ml)
  • 8 slices baguette, about 1 inch thick
  • 2 tbsp olive oil (30 ml)
  • 4 oz Gruyère cheese, grated (approximately 113g)

Instructions:

  1. Heat olive oil and butter in a Dutch oven over medium-low heat. Add onions, sugar, salt, and pepper. Cook, stirring occasionally, until deeply caramelized, about 1 hour, reducing heat if necessary to prevent burning.
  2. Add sherry to the pot and scrape up any browned bits from the bottom. Increase heat to medium and cook for 2 minutes, allowing the alcohol to evaporate.
  3. Add beef broth, thyme, bay leaf, and Worcestershire sauce to the pot. Bring to a simmer, then reduce heat to low and cook for 30 minutes, allowing the flavors to meld. Remove thyme sprigs and bay leaf before serving. Taste and adjust seasoning with salt and pepper as needed.
  4. Preheat oven to 400°F (200°C). Brush baguette slices with olive oil and arrange on a baking sheet. Bake for 5-7 minutes, or until lightly toasted.
  5. Ladle soup into oven-safe bowls. Top each bowl with two baguette slices and sprinkle generously with grated Gruyère cheese. Place bowls on a baking sheet and broil for 2-3 minutes, or until cheese is melted, bubbly, and lightly browned. Watch carefully to prevent burning.
  6. Let cool slightly before serving.