French Onion Soup Recipe
crostini / gruyère cheese*vegetarian
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Ingredients
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Soup
Crostini & Topping
Method
Soup
- 1
Prepare onions
Peel and thinly slice enough yellow onions to yield about 6 cups. Aim for even slices about 1/8 inch thick so they caramelize uniformly.
- 2
Caramelize onions
In a large heavy-bottomed pot or Dutch oven, heat 1 tablespoon olive oil and 3 tablespoons unsalted butter over medium heat. Add the sliced onions, 1 teaspoon kosher salt and 1 teaspoon granulated sugar. Cook, stirring often, until onions are deeply golden brown and richly caramelized, 35–45 minutes. Reduce heat if they begin to burn; scrape browned bits from the bottom occasionally.
- 3
Deglaze
When onions are deeply caramelized, sprinkle 1 tablespoon flour over them and cook 1–2 minutes more to remove the raw flour taste. Pour in 1/2 cup dry white wine (or vermouth) and scrape the fond from the bottom of the pot with a wooden spoon, letting the wine reduce for 1–2 minutes.
- 4
Simmer soup
Add 6 cups vegetable broth, 1 teaspoon vegetarian bouillon (if using), 2 tablespoons fresh thyme (or two sprigs), and 1 bay leaf. Bring to a gentle simmer, then reduce heat to low and cook uncovered for 20–25 minutes to let flavors meld. Season with 1/2 teaspoon freshly ground black pepper and additional salt to taste (start with another 1/2 teaspoon). Remove thyme sprigs and bay leaf before serving.
Crostini & Assembly
- 5
Prepare crostini
Preheat oven to 425°F (220°C). Arrange 12 baguette slices on a baking sheet. Lightly brush both sides with 2 tablespoons olive oil (or melted butter). Bake until golden and crisp, about 6–8 minutes, flipping once. If using, rub one side of each warm crostini with the cut garlic clove for a hint of garlic.
- 6
Ladle and top
Preheat broiler. Divide the hot soup into oven-safe bowls (6 bowls, about 1 to 1 1/4 cups soup per serving). Place one or two crostini on top of each bowl of soup (or place crostini on top of the rim). Generously mound about 1/3 to 1/2 cup grated Gruyère on each bowl so cheese covers bread and rim. Sprinkle about 1 tablespoon grated Parmesan over each, if using.
- 7
Melt cheese
Place bowls on a baking sheet and under the broiler 4–6 inches from the heat until the cheese is bubbling and golden brown, 2–4 minutes. Watch carefully to prevent burning. Alternatively, bake at 400°F (200°C) until cheese melts and browns, about 6–8 minutes.
- 8
Serve
Carefully remove hot bowls from oven (use oven mitts). Let rest 1–2 minutes, then serve immediately. Garnish with a small thyme sprig if desired.