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of field, food photography, natural textures, high detail, no text, no watermark] [ALT TEXT: Bowl of French onion soup with melted Gruyere crust and toasted baguette

French Onion Soup

Deeply caramelized onions in a rich beef broth, topped with toasted baguette and broiled Gruyere.
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Prep Time 20 minutes
Cook Time 1 hour 45 minutes
Total Time 2 hours 5 minutes
Servings: 6
Course: Appetizer, Soup
Cuisine: French
Calories: 340
Ingredients Method Notes

Ingredients
  

  • 3 pounds 1.4 kg yellow onions, halved and thinly sliced
  • 4 tablespoons 55 g unsalted butter
  • 1 tablespoon 15 ml olive oil
  • 1 teaspoon 5 g kosher salt
  • 1/2 teaspoon 2 g sugar, optional
  • 2 cloves garlic minced
  • 6 cups 1.4 L beef broth, low sodium recommended
  • 1 cup 240 ml water
  • 2 tablespoons 30 ml sherry vinegar
  • 2 sprigs fresh thyme
  • 1 bay leaf
  • 1 tablespoon 15 ml Worcestershire sauce
  • Kosher salt and black pepper to taste
  • 1 baguette sliced 1/2 inch thick and toasted
  • 8 ounces 225 g Gruyere cheese, grated
  • 1/4 cup 25 g Parmesan, grated

Method
 

  1. Melt butter and olive oil over medium low heat, add onions and salt.
  2. Caramelize 45 to 55 minutes over medium low heat, deglazing with broth in stages as fond builds.
  3. Stir in garlic, cook 1 minute, then deglaze with 1 cup broth.
  4. Add remaining broth, water, sherry vinegar, thyme, bay leaf, and Worcestershire; simmer uncovered 25 minutes.
  5. Ladle into oven safe crocks, top with toast and cheese, and broil 2 to 4 minutes until bubbling and golden.
  6. Rest 2 minutes before serving.

Notes

The onions need the full 45 to 55 minutes; rushing this step is the most common reason the soup falls short.
Beef broth gives the deepest flavor, but a well seasoned mushroom or vegetable broth works for a vegetarian version.
The onion base can be made up to 2 days ahead and refrigerated separately from the broth.
Storage Notes:
Refrigerate the onion base and broth up to 4 days, bread and cheese added only at reheating.
Freeze the onion base up to 3 months; skip freezing once bread and cheese are on.
Reheat gently on the stove, then rebuild and broil individual bowls fresh.