French Onion Soup

French onion soup with deeply caramelised onions, savoury stock and toasted bread topped with melted cheese.

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The sweetness in French onion soup comes from slowly browned onions, not added sugar. Giving them enough time is what creates the soup’s deep flavour.

Ingredients

• 1.2 kg yellow onions (thinly sliced)
• 50 g unsalted butter
• 1 tbsp olive oil
• 2 garlic cloves (minced)
• 1 tbsp plain flour
• 150 ml dry white wine
• 1.5 litres beef or vegetable stock (hot)
• 4 sprigs thyme
• 1 bay leaf
• 1 tsp salt (plus more to taste)
• 0.5 tsp black pepper
• 12 slices baguette (toasted)
• 180 g Gruyère cheese (grated)

Step-by-step method

1. Melt the butter with the olive oil in a wide heavy pot over medium-low heat. Add the onions and salt and stir thoroughly.
2. Cook the onions slowly for 35–45 minutes, stirring every few minutes. As they darken, stir more often and scrape up any browned bits from the bottom.
3. When the onions are deep golden brown and reduced significantly, add the garlic and cook for 30 seconds.
4. Sprinkle over the flour and stir for 1 minute. Pour in the wine and scrape the bottom of the pot until the browned layer dissolves into the liquid.
5. Add the hot stock, thyme, bay leaf and black pepper. Bring to a gentle simmer and cook uncovered for 25–30 minutes.
6. Taste and adjust the salt, then remove the thyme stems and bay leaf.
7. Preheat the grill or broiler. Ladle the soup into heatproof bowls set on a baking tray, place toasted baguette slices on top and cover generously with grated Gruyère.
8. Grill for 2–4 minutes until the cheese is melted, bubbling and browned in spots. Let the bowls stand for a minute before serving because they will be extremely hot.