French Recipes for Beginners: Easy Onion Soup Recipe

French onion soup, or soupe à l’oignon gratinée, is a French bistro-style soup of deeply browned onions simmered in broth and finished with toasted baguette and melted cheese. This beginner-friendly version uses an ordinary pot and familiar ingredients; steady, patient cooking gives the onions their rich flavor, while the toppings make the soup feel special.

Ingredients

3 lb (1.36 kg) yellow onions, about 6 medium, peeled and thinly sliced
3 tbsp (42 g) unsalted butter
1 tbsp (15 ml) olive oil
1 tsp (5 g) fine salt, plus more to taste
½ tsp (2 g) granulated sugar, optional, to encourage browning
2 tbsp (16 g) all-purpose flour
½ cup (120 ml) dry white wine, or additional broth
6 cups (1.42 L) beef broth; use vegetable broth for a vegetarian soup
2 fresh thyme sprigs, or ½ tsp (1 g) dried thyme
1 bay leaf
¼ tsp (0.5 g) freshly ground black pepper, plus more to taste
8 baguette slices, each about ½ inch (1.3 cm) thick
1½ cups (150 g) grated Gruyère cheese

Instructions

Slice the onions. Cut each peeled onion in half from root to tip, set the flat sides down, and slice thinly from end to end. Aim for slices of similar thickness so they soften at about the same rate. A little variation is fine; very thick pieces simply need more time.
Soften and brown them. Melt the butter with the olive oil in a large, heavy pot over medium heat. Add the onions, salt, and optional sugar, then stir to coat. Cook uncovered for about 10 minutes, stirring every few minutes, until the onions have softened and released moisture. Reduce the heat to medium-low and continue cooking for 35–40 minutes, stirring and scraping the bottom every 5 minutes or so. The onions should become very soft and turn a deep golden brown. If browned bits begin to stick before the onions are ready, lower the heat and stir in a tablespoon of water.
Thicken and deglaze. Sprinkle the flour over the onions and stir for 1 minute so it no longer looks powdery. Pour in the wine and scrape the base of the pot with a wooden spoon to loosen the browned flavor. Let it bubble for 1–2 minutes. If you prefer not to use wine, replace it with the same amount of broth; the soup will be a little less aromatic but still savory.
Simmer the soup. Add the broth, thyme, bay leaf, and black pepper. Bring the liquid to a gentle boil, then lower the heat and simmer uncovered for 20 minutes. Stir occasionally. Remove the thyme stems and bay leaf, taste, and add salt or pepper as needed. Broth varies in saltiness, so adjust only after the soup has simmered.
Toast the baguette. While the soup simmers, heat the oven to 425°F (220°C). Arrange the baguette slices on a baking sheet and toast for about 3 minutes per side, until dry and lightly golden. Keep an eye on them: thin slices can brown quickly. Set the oven to broil when the toast is ready.
Top and broil. Ladle the hot soup into four broiler-safe bowls set on a sturdy baking sheet. Place two toast slices on each bowl and scatter the Gruyère evenly over the bread. Broil, watching continuously, for 2–4 minutes, until the cheese is melted and bubbling with browned spots. Broilers vary, so do not walk away. Use oven mitts and move the baking sheet carefully; the bowls and handles will be extremely hot. If your bowls are not broiler-safe, put the cheese-topped toast on the baking sheet, broil it there, and float a piece on each bowl of soup.

Tips

Give the onions time. Their gradual browning—not extra sugar—is the main source of the soup’s sweetness and depth. Keep the heat moderate and stir often enough to prevent scorching. If they are still pale after 35 minutes, continue cooking; the color matters more than the exact minute.
Choose your broth thoughtfully. Beef broth gives a fuller, classic bistro-style flavor. Vegetable broth works well if you want a meat-free version, though its taste will be lighter. Low-sodium broth makes it easier to control the salt at the end.
Use a practical cheese swap. Gruyère is a traditional-feeling choice for the gratinéed topping, but it may cost more or be harder to find. Comté is a close substitute; Emmental or Swiss cheese melts well but tastes milder. Pre-grated cheese is convenient, though freshly grated cheese generally melts more smoothly.
Prevent a bitter, burnt base. Dark golden-brown onion bits add flavor; blackened ones taste bitter. If the pot gets too hot, turn down the burner and add a small splash of water to loosen the bottom before continuing.

Serving Suggestions

Serve the soup as soon as the cheese has bubbled, while the toast is still crisp on top and beginning to soften where it meets the broth. Set each hot bowl on a heatproof plate and offer a spoon and a fork: the spoon is useful for the broth, while the fork helps manage the bread and melted cheese. A simple green salad with a sharp vinaigrette makes a refreshing contrast to the rich, savory soup. If serving it as a first course, a smaller bowl with one slice of baguette is usually enough; for a generous main course, use the full portion and add salad or steamed green beans.

Variations

Make it vegetarian: Choose vegetable broth and check that the cheese is made with a vegetarian-friendly rennet if that matters to your guests. The result will not taste exactly like beef-broth soup, but the browned onions still provide plenty of flavor.

Skip the alcohol: Replace the white wine with broth, as described in the method. A teaspoon of cider vinegar stirred in at the end can add a little brightness if the soup tastes flat, but add it gradually so it does not become sharp.

Change the herbs or cheese: Use dried thyme if fresh is unavailable, or add a small pinch of dried marjoram. Comté is an excellent alternative to Gruyère; Swiss or Emmental makes a milder topping. Avoid adding a large amount of extra cheese to the soup itself, since it can turn stringy rather than melting evenly over the toast.

Make a lighter topping: Use one baguette slice per bowl instead of two, or serve the soup with the cheesy toast on the side. That keeps the bread crisp longer and lets everyone decide how much to add.

Storage and Reheating

For the best texture, store the soup and toasted bread separately. Let the soup cool briefly, then refrigerate it in a covered container within 2 hours of cooking. It keeps for 3–4 days in the refrigerator. Refrigerate leftover cheese-topped toast separately, though it will soften; making fresh toast when you reheat the soup gives the closest result to serving it newly made.

Reheat only the amount you plan to eat in a saucepan over medium-low heat, stirring occasionally until steaming throughout. USDA FSIS guidance is to reheat leftovers to 165°F (74°C); check the soup with a food thermometer before serving. Add a splash of broth or water if it has thickened in the refrigerator. Toast fresh baguette, add cheese, and broil as directed. The soup without its bread topping can also be frozen in a freezer-safe container for up to 3 months for best quality. Thaw it in the refrigerator before reheating; do not freeze the assembled soup bowls.

Frequently Asked Questions

Why are my onions not turning brown?

They may be crowded, too wet, or cooking over too low a heat. A wide, heavy pot helps moisture evaporate, but onions still take time. Keep cooking uncovered and stir regularly. If they are steaming in a deep layer of liquid, maintain a gentle medium-low heat until the moisture cooks off, then watch closely as browning begins.

Can I make French onion soup without wine?

Yes. Use an equal amount of broth to deglaze the pot. Wine adds a little acidity and aroma, but it is not essential to the recipe. Taste the finished soup before serving; if it seems heavy, a small splash of cider vinegar can brighten it.

What can I use instead of Gruyère?

Comté has a similarly savory, nutty character and melts well. Emmental and Swiss cheese are easier-to-find alternatives with a gentler flavor. If you use mozzarella, expect a stretchier topping with less of the distinctive savory taste associated with Gruyère.

Can I prepare the soup ahead?

Yes. Make the soup through the simmering step, cool it, and refrigerate it for up to 3–4 days. Reheat it to 165°F (74°C), then toast the baguette and add the cheese just before serving. Keeping the bread and soup separate prevents the toast from becoming soggy.

Do I need special bowls?

Broiler-safe soup crocks are useful, but they are not required. Broil the cheese on the toast on a baking sheet, then place the finished toast on bowls of hot soup. Use bowls that can safely hold hot liquid, and handle the baking sheet and toasted bread with care.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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