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mary berry french onion soup

Mary Berry French Onion Soup

This Mary Berry French onion soup features slowly caramelized onions cooked until deeply golden and sweet, combined with rich beef stock for maximum flavor. Topped with crusty bread and melted Gruyère cheese, this classic French bistro dish delivers restaurant-quality comfort food at home. Perfect as an elegant starter or satisfying light meal, this trusted recipe requires patience but rewards you with incredible depth of flavor.
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Prep Time 15 minutes
Cook Time 1 hour
Servings: 8
Course: Soup
Cuisine: French
Calories: 355
Ingredients Method Notes

Ingredients
  

  • 3 tbsp butter
  • 1 tbsp sunflower oil
  • 2 lb 1 kg large white onions, thinly sliced
  • 2 tsp granulated sugar
  • ¼ cup all-purpose flour
  • 7½ cups vegetable chicken, or beef stock
  • Salt and black pepper to taste
  • 8 Gruyère croûtes

Method
 

  1. Begin by melting 3 tbsp butter with 1 tbsp sunflower oil in a large saucepan over medium heat. Once the butter is melted and foamy, add the 2 lb of thinly sliced large white onions along with 2 tsp granulated sugar. The sugar helps accelerate the caramelization process and deepens the natural sweetness of the onions.
  2. Stir the onions frequently as they cook, allowing them to slowly turn golden brown and develop rich, complex flavors. This caramelization step typically takes 20-30 minutes and is indispensable to achieving the soup's signature deep, savory taste—do not rush this process or attempt to speed it up with high heat, as this will result in burnt onions rather than properly caramelized ones.
  3. Once the onions are deeply caramelized, sprinkle ¼ cup all-purpose flour evenly over the onions and stir constantly for 1-2 minutes. This flour acts as a thickening agent and helps create the soup's characteristic body. Gradually pour in 7½ cups of your chosen stock—vegetable, chicken, or beef—while continuing to stir to prevent lumps from forming.
  4. Bring the mixture to a boil, then reduce the heat to low, cover the saucepan, and simmer for 35 minutes, stirring occasionally. During this time, the flavors will meld and intensify.
  5. After simmering, taste the soup and adjust the seasoning with salt and black pepper as needed. Ladle the hot soup into warmed bowls and float one Gruyère croûte in each bowl.
  6. Serve immediately while the soup is piping hot and the cheese on the croûte is warm and slightly softened by the heat of the broth.

Notes

What is the Secret to Good French Onion Soup?

The secret to exceptional French onion soup lies in properly caramelizing the onions, a process that cannot be rushed. Slow cooking onions over medium-low heat for 30-40 minutes allows their natural sugars to develop, creating deep, sweet, complex flavors essential to the dish. Patience is crucial: resist the temptation to increase the heat, as this burns rather than caramelizes the onions. Using quality beef stock adds richness and depth, while a splash of wine or sherry enhances the savory notes. Finally, choosing the right cheese matters. Authentic Gruyère melts beautifully and provides nutty, complex flavor that complements the sweet onions perfectly, creating that iconic golden, bubbling top.