Description
A classic and hearty French Onion Soup featuring caramelized yellow onions simmered in a flavorful broth, topped with toasted baguette slices and melted Gruyère cheese. This comforting recipe is perfect for a cozy meal and highlights the rich depth of slow-cooked onions balanced with fresh thyme and a touch of balsamic vinegar.
Ingredients
Scale
Soup
- 6 tablespoons extra-virgin olive oil
- 3 pounds medium yellow onions, halved and thinly sliced
- ¾ teaspoon sea salt
- 1½ tablespoons balsamic vinegar
- 1½ tablespoons tamari
- 1½ tablespoons fresh thyme leaves
- 3 garlic cloves, minced
- 3 tablespoons all-purpose white flour
- 1 cup dry white wine
- 6 cups vegetable broth
- Freshly ground black pepper, to taste
Topping
- Baguette slices
- Gruyère cheese, aged cheddar, and/or Parmesan cheese
- Fresh thyme
- Pinch of red pepper flakes (optional)
Instructions
- Caramelize the onions: Heat the olive oil in a large pot or Dutch oven over medium heat. Add the sliced onions, sea salt, and several grinds of black pepper, tossing to combine. Reduce the heat to low and cook the onions for about 40 minutes, stirring every few minutes until they become very soft.
- Brown the onions: Increase the heat to medium and continue cooking the onions for an additional 15 to 20 minutes, stirring often, until they are golden brown and caramelized.
- Add flavorings: Stir in the balsamic vinegar, tamari, fresh thyme leaves, and minced garlic, mixing well to incorporate the flavors.
- Thicken the soup: Sprinkle the flour over the onions, stir thoroughly, and cook for 2 minutes to eliminate the raw flour taste.
- Deglaze the pot: Pour in the white wine and cook for about 2 minutes, allowing the wine to reduce and evaporate slightly.
- Simmer the soup: Add the vegetable broth, stir well, and simmer the soup over medium heat for 30 minutes to meld the flavors together.
- Prepare the topping: Preheat the oven to 450°F (232°C) and line a baking sheet with parchment paper. Place the baguette slices on the sheet, top each with a generous amount of Gruyère, aged cheddar, and/or Parmesan cheese.
- Bake the crostini: Bake the cheese-topped baguette slices in the oven for 8 to 10 minutes until the bread is toasted and the cheese has melted.
- Serve: Ladle the hot soup into ramekins or bowls, top each serving with a toasted cheese baguette, fresh thyme sprigs, and optionally a pinch of red pepper flakes for a subtle heat.
Notes
- For a richer flavor, use beef broth instead of vegetable broth if not seeking a vegetarian option.
- You can substitute tamari with soy sauce if needed.
- Caramelizing onions slowly is key to achieving the deep, sweet flavor essential for French onion soup.
- If you don’t have Gruyère cheese, aged cheddar or Parmesan are excellent alternatives.
- Make sure to watch the baguette slices closely while baking to avoid burning the cheese.
- Leftover soup tastes even better the next day as the flavors intensify.
Nutrition
- Serving Size: 1 bowl (about 1.5 cups)
- Calories: 320 kcal
- Sugar: 8 g
- Sodium: 680 mg
- Fat: 18 g
- Saturated Fat: 6 g
- Unsaturated Fat: 11 g
- Trans Fat: 0 g
- Carbohydrates: 28 g
- Fiber: 3 g
- Protein: 10 g
- Cholesterol: 20 mg
