Ingredients:

  • 1.13 kg Yellow onions, thinly sliced
  • 42 g Unsalted butter
  • 30 ml Extra virgin olive oil
  • 3 g Baking soda
  • 6 g Granulated sugar
  • 6 g Kosher salt
  • 1.42 L Beef stock (high quality, low sodium)
  • 120 ml Dry white wine (such as Pinot Grigio or Sauvignon Blanc)
  • 30 ml Sherry or Brandy (optional, for depth)
  • 2 sprigs Fresh thyme
  • 1 bay leaf
  • 15 g All-purpose flour
  • Black pepper to taste
  • 1 French baguette, sliced into 1-inch rounds
  • 225 g Gruyère cheese, grated
  • 115 g Parmesan cheese, grated

Instructions:

  1. Heat the butter and olive oil over medium-high heat. Add the sliced onions, stirring to coat. Sprinkle in the sugar, salt, and baking soda. Sauté for 15–20 minutes, stirring occasionally.
  2. Sprinkle the flour over the browned onions and cook for 2 minutes to remove the raw flour taste. Pour in the white wine (and sherry if using), scraping the bottom of the pot vigorously to incorporate the fond.
  3. Pour in the beef stock, add the thyme and bay leaf, and bring to a simmer. Reduce heat to low and let it bubble gently for 20 minutes to meld the flavors.
  4. Preheat your broiler. Toast baguette slices on a baking sheet until lightly golden. Ladle the hot soup into oven-safe crocks. Place a toasted bread slice (or two) on top of the liquid.