How to Make Authentic French Onion Soup (Soupe à l'Oignon Gratinée)

Simple Summary

Soupe à l'Oignon Gratinée is a classic French onion soup, rich with caramelized onions and topped with a layer of melted cheese. This comforting dish is perfect for cold evenings or as an elegant starter.

Recipe Details

• Prep Time: 20 minutes
• Cook Time: 1 hour 30 minutes
• Total Time: 1 hour 50 minutes
• Servings: 6
• Difficulty: Intermediate

Ingredients

• 6 large yellow onions, thinly sliced
• 4 tablespoons unsalted butter
• 2 tablespoons olive oil
• 1 teaspoon sugar
• 1 teaspoon salt
• 1/4 cup all-purpose flour
• 8 cups beef stock
• 1/2 cup dry white wine
• 2 bay leaves
• 4 sprigs fresh thyme
• 1 baguette, sliced into 1-inch rounds
• 2 cloves garlic, peeled
• 2 cups grated Gruyère cheese
• 1/4 cup grated Parmesan cheese
• Salt and freshly ground black pepper to taste

Instructions

1. In a large Dutch oven, melt butter with olive oil over medium heat. Add sliced onions, sugar, and salt. Cook for about 45 minutes, stirring occasionally, until onions are deeply caramelized and golden brown.

2. Sprinkle flour over the onions and cook for 1-2 minutes, stirring constantly.

3. Gradually add beef stock and white wine, stirring continuously to prevent lumps. Add bay leaves and thyme sprigs.

4. Bring the soup to a simmer and cook for 30 minutes, stirring occasionally. Season with salt and pepper to taste.

5. While the soup simmers, preheat your oven's broiler. Toast baguette slices until golden brown on both sides. Rub each slice with a clove of garlic.

6. Ladle the hot soup into oven-safe bowls. Place a toasted baguette slice on top of each bowl of soup.

7. Generously sprinkle grated Gruyère and Parmesan cheese over the bread and around the edges of the bowl.

8. Place the bowls on a baking sheet and broil for 2-3 minutes, or until the cheese is melted, bubbly, and lightly browned.

9. Carefully remove from the oven and let cool for a few minutes before serving.

Chef's Notes

• For the best flavor, use a mix of sweet onions like Vidalia and yellow onions.
• If you can't find Gruyère, Emmental or Comté cheese make good substitutes.
• The soup can be made ahead and refrigerated for up to 3 days. Reheat gently before adding bread and cheese for broiling.
• For a vegetarian version, use vegetable stock instead of beef stock.

Nutritional Info

Per serving: Approximately 420 calories, 22g protein, 25g fat (12g saturated), 35g carbohydrates, 3g fiber. Rich in vitamins A and C, calcium, and iron.

Serving Suggestions

Serve this Soupe à l'Oignon Gratinée as a hearty starter or main course. Pair with a crisp green salad and a glass of dry white wine like Chablis or Sauvignon Blanc. For a complete French-inspired meal, follow with a simple roast chicken and finish with a light fruit tart for dessert.