Classic French Onion Soup

Ingredients

• 6 large onions, thinly sliced
• 3 tbsp butter
• 1 tbsp olive oil
• 1 tsp sugar
• Salt and black pepper
• 3 cloves garlic, minced
• 2/3 cup (150ml) dry white wine
• 4 cups (1L) beef or vegetable stock
• 1 tbsp fresh thyme leaves (or 1 tsp dried)
• 4 thick slices crusty bread
• 2 cups (7 oz / 200g) grated Gruyère cheese

Instructions

1. Melt butter with olive oil in a large heavy-bottomed pot over medium heat.
2. Add onions and a pinch of salt. Cook for 40-50 minutes, stirring every 5 minutes. Don't rush this. Properly caramelized onions are deeply golden brown and sweet, not just soft and translucent. If they're sticking, add a splash of water and scrape up the fond—that's pure flavor.
3. Add sugar halfway through to help caramelization. If they start sticking, add a splash of water and scrape the bottom.
4. Add garlic and cook 1 minute.
5. Pour in wine and scrape up any brown bits from the bottom. Let it reduce by half.
6. Add stock and thyme. Bring to a simmer and cook 15 minutes. Season with salt and pepper.
7. Ladle into oven-safe bowls. Top with bread and a generous pile of Gruyère.
8. Grill under a hot broiler for 3-4 minutes until cheese is bubbling and golden.

Notes

Critical insight: The entire recipe hinges on the onions. Properly caramelized onions take 40 to 50 minutes. If a recipe or a person tells you it takes 10 minutes, they're lying. Rushing this step gives you boiled, pale onions instead of the deeply sweet, jammy foundation this soup requires.

Substitutions: Gruyère is traditional for its nutty flavor and perfect melting quality, but Comté or even a high-quality low-moisture mozzarella can work in a pinch. Swap the beef stock for mushroom or vegetable stock to make the dish vegetarian.

Storage: The soup base (without the bread and cheese) can be kept in the fridge for up to 5 days, or frozen for up to 3 months. In fact, making the broth a day ahead deepens the flavor. Reheat the broth, then add the fresh toast and cheese right before broiling.

Variations: Add a splash of cognac or brandy along with the white wine for an even deeper, richer flavor profile. For a thicker soup, sprinkle 1 tablespoon of flour over the caramelized onions and cook for a minute before adding the liquids.

Pairs with: Serve alongside a crisp green salad with a sharp vinaigrette to cut through the heavy richness, or follow it up with Crispy Chicken Thighs for a bistro-style dinner.