Ingredients:

  • Tbsp unsalted butter
  • lbs yellow onions, thinly sliced pole-to-pole
  • tsp kosher salt, plus more to taste
  • tsp granulated sugar
  • Tbsp all-purpose flour
  • /2 cup dry sherry or dry white wine
  • cups good quality beef broth (low sodium)
  • sprigs fresh thyme
  • bay leaf
  • Freshly ground black pepper to taste
  • slices crusty baguette or sourdough, 1-inch thick
  • oz freshly grated Gruyère cheese

Instructions:

  1. Melt butter in a large, heavy-bottomed Dutch oven over medium heat. Add onions, salt, and sugar. Cook, stirring frequently for the first 15 minutes.
  2. Reduce heat to medium-low and continue cooking for 30–40 minutes, scraping the bottom often, until onions turn deep mahogany brown (caramelised).
  3. Sprinkle flour over the onions and stir constantly for 2 minutes.
  4. Pour in the dry sherry/wine. Scrape up all the browned bits (the fond) stuck to the bottom of the pot vigorously. Let the liquid bubble and reduce by half (about 3 minutes).
  5. Pour in the beef broth. Add thyme sprigs and the bay leaf. Bring to a gentle simmer, then reduce heat to low. Cover loosely and cook for 15 minutes to allow flavours to marry. Remove and discard the thyme and bay leaf. Taste and adjust salt/pepper.
  6. While the soup simmers, toast the baguette slices lightly under the broiler until crisp.
  7. Preheat your oven’s broiler/grill to high. Ladle the hot soup into 4 oven-safe crocks, filling them about 3/4 full. Float one toasted baguette slice on top of the soup in each crock.
  8. Cover the bread entirely with a generous layer of grated Gruyère cheese. Place crocks on a sturdy baking sheet and broil for 3–5 minutes, watching carefully, until the cheese is melted, bubbly, and deeply golden brown. Serve immediately.