French Onion Soup

Ingredients you'll need

Oil - We cook the onions in olive oil and butter. Use any oil suitable for sautéing.

Onions - Yellow onions work best, but white onions are a good substitute.

Wine - White wine deglazes the pot after caramelizing the onions. Small-format bottles work well if you do not want to open a full bottle.

Broth - Beef broth is traditional. Chicken broth or vegetable broth also work.

Herbs and spices - Bay leaf, fresh thyme, kosher salt, and black pepper enhance the flavor of the onions and broth.

Bread - Use a French baguette or another sturdy, crusty bread.

Cheese - Gruyère, provolone, or Swiss melt well. Gouda or mozzarella (not fresh mozzarella) work in a pinch.

📖 See the recipe card for quantities and preparation.

Let's get cooking

Heat the olive oil and butter in a large pot over medium heat. When the butter melts and begins to foam, add the sliced onions. It will look like there are too many onions, but they will reduce significantly as they cook.

Stir the onions occasionally at first. As they soften and begin to turn a light caramel color, stir more often and scrape the bottom of the pot to prevent burning.

The onions when they are first added to the pot.

After 15 minutes, the onions start to reduce in volume.

After 25 minutes, there is a noticeable reduction, and they begin to turn a soft golden color.

The onions continue to reduce and caramelize. At this stage, stir frequently, almost constantly.

After 45-50 minutes, the onions turn a rich golden-brown color. The brown bits on the bottom of the pot are sweet, caramelized onions. If they sit too long, they will burn and turn bitter.

Next, add the white wine to the pot. Gently scrape any bits off the bottom of the pot. Cook the wine with the onions for 1-2 minutes, or until most of the liquid has cooked out.

Add the beef broth, bay leaf, thyme, salt, and pepper to the pot. Stir well.

Raise the heat to medium-high and bring the broth to a simmer. Then lower the heat to medium-low, cover, and cook for 20 minutes to let the flavors come together. Stir occasionally. Keep the liquid at a simmer; if it's boiling too vigorously, lower the heat.

Build the soup

• Preheat the oven to 250°F. Slice the bread into ½-1-inch rounds and arrange them on a baking sheet. Lightly toast the bread for about 5-7 minutes.
• When the soup is done, take the pot off the heat and discard the bay leaf and thyme. Use tongs to fish them out.
• Taste the soup and add salt if needed. As a reference, we did not add any to ours.
• Preheat the oven to the broil setting (use low broil if your oven has that option). Ladle the soup into individual, broiler-safe bowls (such as soup crocks or ramekins).
• Place one or two slices of bread on top, depending on the size of the bowl. Add one or two slices of cheese over the bread.
• Set the bowls on a baking sheet to keep the cheese from dripping onto the oven and to make them easier to handle.
• Broil until the cheese melts and turns golden in spots. This step only takes a few minutes. Check the bowls every minute and stay by the oven. Turn on the oven light and keep a close eye on the cheese so it does not burn.
• Garnish with fresh thyme or chopped parsley, if desired. Serve and enjoy.

Storing instructions

Only prepare the servings you plan to finish with bread and cheese. Store leftover soup (without bread and cheese) in an airtight container in the refrigerator for 3-4 days. To freeze, leave 1-2 inches of space in the container to allow for expansion and freeze for 2-3 months.

Reheat the soup in a saucepan or the microwave until hot and steamy.

Food safety: According to U.S. Department of Agriculture guidelines, do not leave cooked food out for more than two hours, or more than one hour if the ambient temperature is above 90°F. Always reheat leftovers to at least 165°F. For more information on food storage and safety, visit the U.S. Department of Agriculture and foodsafety.gov.