French Onion Soup With Sherry: A Deeply Savory Recipe

French onion soup with sherry is a French-inspired bowl of slowly caramelized onions simmered in savory broth, finished with toasted bread and melted cheese. Dry sherry adds a rounded, nutty note that balances the onions’ sweetness without overpowering them; the key is giving the onions enough time to brown gradually.

Ingredients

3 lb (1.36 kg) yellow onions, peeled, halved, and thinly sliced
3 tbsp (42 g) unsalted butter
1 tbsp (15 ml) olive oil
1 tsp (6 g) fine sea salt, plus more to taste
1/2 tsp (1 g) freshly ground black pepper
1 tsp (5 g) granulated sugar, optional, to help encourage browning
2 tbsp (16 g) all-purpose flour
1/2 cup (120 ml) dry sherry
8 cups (1.9 L) low-sodium beef broth, or vegetable broth
2 sprigs fresh thyme, or 1/2 tsp (0.5 g) dried thyme
1 bay leaf
1 tbsp (15 ml) Worcestershire sauce
1 baguette, about 12 oz (340 g), cut into 12 slices about 1/2 inch (1.3 cm) thick
2 cups (200 g) grated Gruyère cheese
2 tbsp (8 g) finely chopped fresh parsley, optional

Instructions

Prepare the onions and bread. Peel, halve, and slice the onions evenly, aiming for strips about 1/4 inch (6 mm) thick so they soften at a similar pace. Set a rack in the upper third of the oven and preheat to 400°F (200°C). Arrange the baguette slices on a baking sheet. You can grate the cheese while the onions cook.
Caramelize the onions slowly. Set a large, heavy Dutch oven or soup pot over medium heat. Add the butter and olive oil. When the butter has melted, stir in the onions, salt, pepper, and optional sugar. Cook for about 55 minutes, stirring every few minutes at first and more frequently as the onions become soft and golden. If brown bits start sticking to the bottom, lower the heat slightly and stir in a tablespoon or two of water to loosen them. The onions are ready when they are deeply golden, greatly reduced in volume, and sweet-smelling, not merely translucent. Do not rush this stage with high heat; scorched onions can taste bitter.
Thicken and deglaze. Sprinkle the flour over the onions and stir continuously for 1 minute so it coats them without forming dry clumps. Pour in the sherry carefully and scrape the bottom of the pot with a wooden spoon to release the browned bits. Let it bubble for 2 to 3 minutes, until the sharp alcohol aroma has softened.
Simmer the soup. Add the broth, thyme, bay leaf, and Worcestershire sauce. Bring the liquid to a gentle boil, then reduce the heat so it simmers steadily but not vigorously. Cook uncovered for 30 minutes, stirring occasionally. Remove the thyme stems and bay leaf. Taste and adjust the salt and pepper; the right amount depends on the broth and cheese. If the soup tastes too sweet, a small splash of sherry or a little extra Worcestershire can add balance.
Toast the baguette. While the soup simmers, bake the slices at 400°F (200°C) for about 8 minutes, turning them once, until dry and lightly golden. They should be crisp enough to hold their shape when topped with soup, but they do not need to be browned deeply. Remove the tray and set the oven to broil. If your oven’s broiler requires a different setting, use its high setting and keep the bread close enough to toast but not so close that it burns immediately.
Top and broil. Ladle the hot soup into six broiler-safe ovenproof bowls, leaving about 1/2 inch (1.3 cm) of space at the rim. Float one or two baguette slices on each bowl, then divide the Gruyère evenly over the bread, letting a little cheese fall onto the soup. Set the bowls on a sturdy rimmed baking sheet and broil for 2 to 4 minutes, watching continuously, until the cheese is melted, bubbling, and spotted golden. Use oven mitts to remove the tray and let the bowls stand for a few minutes before serving; the soup and bowls will be extremely hot. Garnish with parsley if desired.

Tips

Choose the right sherry. Use dry, drinkable sherry such as fino or amontillado. Avoid sweet cream sherry, which can make the soup cloying, and avoid most cooking sherry, which may be noticeably salty. If sherry is unavailable, use dry white wine; the soup will be brighter and less nutty. For an alcohol-free alternative, use broth with 1 teaspoon (5 ml) cider vinegar, adding more only if needed for balance.
Let the onions take their time. A wide, heavy pot helps moisture evaporate and encourages even browning. Stir and scrape the bottom regularly, but do not keep the heat so high that the edges turn dark before the onions soften. The optional sugar is not necessary; onions brown naturally when cooked patiently.
Adjust for broth and cheese. Low-sodium broth gives you more control over seasoning, especially because Gruyère and Worcestershire contribute salt. Taste after simmering, then add salt gradually. If the broth is already quite salty, start with less salt on the onions.
Make it gluten-free if needed. Use a gluten-free baguette and replace the flour with 1 tablespoon (8 g) cornstarch mixed with 2 tablespoons (30 ml) cold water. Stir the slurry into the simmering soup and cook for a minute or two until lightly thickened. Check that the broth and Worcestershire sauce are also labeled gluten-free.

Serving Suggestions

Serve the soup as soon as the cheese has melted, while the bread is crisp on top and beginning to soak up broth underneath. Set each bowl on a heatproof plate or small board, and warn guests that the crock will stay hot after it leaves the oven. A simple green salad with a sharp vinaigrette makes a fresh counterpoint to the rich broth and cheese. For a larger meal, offer roasted vegetables or a small portion of roast chicken alongside, rather than adding too many heavy sides.

If you do not have individual ovenproof crocks, assemble the topping in a large broiler-safe dish: float the toasted baguette over the soup, scatter the cheese across the surface, and broil until bubbling. Spoon portions into regular bowls at the table. This is easier for serving a group, though each person will not get quite the same browned cheese cap.

Variations

Use vegetable broth: A full-bodied vegetable broth makes the soup meat-free. Look for a broth with a deep, savory flavor, and taste before adding Worcestershire, which may contain anchovies. A vegetarian Worcestershire-style sauce or a teaspoon of soy sauce can provide savory depth, though soy sauce will shift the flavor slightly.

Change the cheese: Comté is close in character to Gruyère, while Emmental melts smoothly with a mild flavor. A mixture of Gruyère and Parmesan gives a more assertive, salty top. If Gruyère is difficult to find, use a good melting Swiss-style cheese; the result will be less nutty but still satisfying.

Make it without wine: Replace the sherry with 1/2 cup (120 ml) broth and add 1 to 2 teaspoons (5 to 10 ml) cider vinegar after the soup simmers. Start with the smaller amount and taste. Vinegar supplies acidity but not sherry’s toasted, nutty character, so the finished soup will taste a little simpler.

Skip the flour: The soup can be made without a thickener. Omit the flour and simmer as directed; the broth will be lighter and clearer rather than slightly velvety. The long-cooked onions still give it plenty of body and flavor.

Storage and Reheating

For the best texture, store the soup and bread topping separately. Transfer leftover soup to shallow containers and refrigerate it within 2 hours of cooking; it keeps for 3 to 4 days. Keep toasted baguette in an airtight container at room temperature for up to 2 days, and refrigerate any grated cheese in a covered container. Do not store soup in its hot serving crocks.

Reheat the soup gently in a saucepan over medium-low heat, stirring occasionally, until steaming hot throughout. If it has thickened in the refrigerator, add a splash of broth or water. For food safety, USDA FSIS advises reheating leftovers to 165°F (74°C); check the center with a food thermometer. Toast fresh bread, ladle the hot soup into ovenproof bowls, add bread and cheese, and broil just before serving. You can freeze the soup without its toppings for up to 3 months; thaw it in the refrigerator before reheating. The onions may soften further after freezing, but the flavor remains good.

Frequently Asked Questions

What kind of sherry is best for French onion soup?
Choose a dry sherry, such as fino or amontillado. Fino is crisp and delicate, while amontillado has a deeper, toasted character. Either works well with caramelized onions. Avoid sweet cream sherry, which can make the broth overly sweet, and check the label on cooking sherry because it is often salted.

Can I make the soup ahead of time?
Yes. Cook the soup through the simmering stage, cool it promptly, and refrigerate it for up to 3 to 4 days. Reheat it to 165°F (74°C), then add toasted bread and cheese and broil shortly before serving. Keeping the topping separate prevents the bread from becoming soggy during storage.

Why are my onions not caramelizing?
They may be releasing moisture faster than it can evaporate, especially if the pot is crowded or the heat is low. Keep the pot uncovered, use a wide heavy pan, and continue cooking until the liquid has cooked away. If the onions begin sticking, scrape the fond up with a small splash of water and lower the heat if necessary. True caramelization takes time; pale, soft onions need longer.

Can I use red or white onions instead of yellow onions?
Yes, though yellow onions are a balanced choice for this soup. Red onions can become sweeter and may give the broth a slightly darker or purplish tint. White onions are sharper and can make a more direct, less sweet soup. Whatever type you use, slice them evenly and cook until deeply golden.

What if I do not have ovenproof soup bowls?
Do not put ordinary bowls under a broiler. Instead, broil the cheese-topped bread on a baking sheet until melted, then float one slice on each bowl of hot soup. Alternatively, assemble the bread and cheese on top of the soup in a large broiler-safe baking dish and portion it after broiling.

Can I make this soup without beef broth?
Yes. Use vegetable broth for a meat-free version, or substitute chicken broth for a lighter flavor. Choose a well-seasoned, relatively low-sodium broth so the onions remain the focus and you can control the final seasoning. If serving vegetarians, check the Worcestershire sauce for anchovies and choose a suitable alternative if needed.

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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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