Ingredients:

  • 3 lbs yellow onions, peeled and thinly sliced
  • 4 Tbsp unsalted butter
  • 1 Tbsp olive oil
  • 1/2 cup dry Sherry or Dry White Wine
  • 2 Tbsp all-purpose flour
  • 6 cups low-sodium beef broth
  • 4 sprigs fresh thyme
  • 1 large bay leaf
  • Salt and freshly ground black pepper to taste
  • 1 small baguette, sliced 1/2 inch thick
  • 6 oz freshly grated Gruyère cheese

Instructions:

  1. Melt butter and oil in a large, heavy-bottomed Dutch oven over medium heat. Add all sliced onions and a pinch of salt. Cook slowly for 15 minutes, stirring occasionally, until softened.
  2. Reduce heat to medium-low. Continue cooking for 45–60 minutes, stirring every 5–7 minutes, scraping up any browned bits (fond). Onions must turn a deep, mahogany brown.
  3. Sprinkle flour over the caramelized onions and stir for 1 minute. Pour in the Sherry/Wine, scraping vigorously to lift all the flavourful brown bits from the bottom of the pot. Cook until the liquid is almost evaporated.
  4. Add the beef broth, thyme bundle, and bay leaf. Bring to a gentle simmer. Partially cover and cook for 30–40 minutes to allow flavours to meld. Remove and discard the thyme and bay leaf. Taste and adjust seasoning.
  5. While the soup simmers, preheat the broiler. Lightly toast the baguette slices on a baking sheet until just starting to crisp.
  6. Ladle the hot soup into oven-safe crocks, ensuring each gets a generous amount of onion. Float one or two toasted baguette slices on top of the soup.
  7. Generously cover the bread entirely with grated Gruyère cheese. Place crocks on the baking sheet and transfer carefully under the hot broiler for 3–5 minutes, watching closely, until the cheese is melted, bubbly, and deeply golden brown.
  8. Serve Immediately, warning diners that the bowls are scorching hot.