French Soup Tureen: Classic Onion Soup for Sharing

French onion soup, or soupe à l’oignon, is a savory French-style soup of slowly browned onions simmered in broth and served with toasted baguette and Gruyère. A tureen makes it easy to bring the soup to the table for sharing; the crisp cheese toasts are best added to individual bowls just before serving.

Ingredients

3 lb yellow onions (1.36 kg), peeled, halved, and thinly sliced
3 tbsp unsalted butter (42 g)
1 tbsp olive oil (15 ml)
1 tsp fine salt (6 g), plus more to taste
1 tsp granulated sugar (4 g), optional, to encourage browning
2 tbsp all-purpose flour (16 g)
1 cup dry white wine (240 ml), such as Sauvignon Blanc, or additional broth
8 cups beef broth (1.9 L), preferably lower-sodium; use vegetable broth for a meat-free version
2 sprigs fresh thyme (about 2 g), or ½ tsp dried thyme (0.5 g)
1 bay leaf (about 0.2 g)
½ tsp freshly ground black pepper (1 g)
1 baguette (about 12 oz / 340 g), cut into 12 slices about ½ inch (1.3 cm) thick
2 cups grated Gruyère cheese (about 200 g)
1 tbsp chopped fresh parsley (4 g), optional, for serving

Instructions

Prepare the onions. Peel, halve, and slice the onions from root to tip into thin, even strips. Keeping the slices similar in thickness helps them soften and brown at a steady pace. Set out the broth, wine, thyme, bay leaf, and remaining ingredients before you start cooking; once the onions are browned, the soup comes together more quickly.
Cook the onions slowly. Melt the butter with the olive oil in a large, heavy-bottomed pot over medium heat. Add the onions, salt, and optional sugar, then stir to coat. Cook for 10 minutes, stirring every couple of minutes, until the onions have softened and begun to release their liquid. Reduce the heat to medium-low and cook for 35 minutes more, stirring frequently and scraping the bottom of the pot. The onions should become very soft and deeply golden brown, not blackened. If browned bits start to stick before the onions are tender, lower the heat and stir in a tablespoon of water.
Stir in the flour and wine. Sprinkle the flour over the onions and stir for 1 minute so it is distributed without dry lumps. Pour in the wine gradually, scraping up the browned bits on the bottom of the pot. Let it bubble for 2 minutes, stirring, until the sharp wine aroma has mellowed. If you prefer to avoid wine, use broth here; the soup will have a slightly less wine-like, but still savory, flavor.
Simmer the soup. Add the broth, thyme, bay leaf, and black pepper. Bring the pot just to a boil, then lower the heat and simmer uncovered for 25 minutes. Stir once or twice, and keep the soup at a gentle bubble rather than a hard boil. Remove and discard the thyme stems and bay leaf. Taste the broth before adding more salt, since packaged broth and cheese can both be salty.
Toast the baguette. While the soup finishes simmering, arrange the bread slices in a single layer on a baking sheet. Toast them under the broiler until dry and lightly golden, about 4 minutes per side; watch closely because broilers can brown bread quickly. Take the tray out and divide the grated Gruyère over the slices. Return it to the broiler for about 3 minutes, watching continuously, until the cheese is melted and bubbling. The bread should be crisp at the edges but not scorched.
Transfer to a tureen and serve. Warm a heat-safe soup tureen with hot water, then empty and dry it. Ladle in the hot soup and carry it to the table. Put the cheese toasts on a platter alongside it, or set one in each bowl after ladling. Do not place an ordinary decorative tureen under the broiler; many serving vessels are not oven-safe, and the separate-toast method keeps the bread crisp as well.

Tips

Give the onions time. The soup’s depth comes from gradual browning, not from adding extra sugar or turning the heat high. Stir often enough to prevent scorching, but let the onions sit against the pot between stirs so they can color. If they look dry or begin to catch, lower the heat and add a small splash of water.
Choose the right pot. A wide, heavy pot gives the onions more contact with the cooking surface and helps them brown evenly. If your pot is narrow, the onions may steam at first; keep cooking and stir as they shrink. Avoid using a thin pan over high heat, where the bottom can burn before the onions soften.
Adjust the broth to your taste. Beef broth gives the soup a classic deep flavor, while vegetable broth makes it suitable for a meat-free meal. If the broth is already salty, wait until the end to season. If the finished soup tastes especially rich or salty, add a little hot water rather than more wine.
Keep the tureen and toasts separate. Add bread to bowls only as they are served. Leaving it floating in the tureen softens the toast and makes it harder to portion the soup neatly. If you do not own a tureen, a warmed serving bowl or a Dutch oven brought carefully to the table works.

Serving Suggestions

For a family-style meal, set the warmed tureen in the center of the table with a ladle and a platter of cheese toasts. Ladle the soup into bowls first, then add a toast to each serving so the crust stays crisp for a little longer. A shallow bowl gives the onions and broth room to spread, while a mug is handy for a smaller, casual portion.

French onion soup is filling, so a simple green salad with a sharp vinaigrette makes a useful contrast. It also pairs well with a modest cheese board, sliced pears, or a plain green salad with crisp leaves. If you are serving it as a first course, make smaller portions and offer the cheese toast on the side. Keep extra parsley separate and scatter a little over the bowls for color, if desired.

Variations

Use vegetable broth: Replace the beef broth with a robust vegetable broth for a meat-free soup. Choose one with a savory, not overly sweet, flavor; some vegetable broths are mild, so taste and adjust the pepper and salt near the end.

Change the cheese: Comté is a close French-style alternative to Gruyère and melts well. Emmental or Swiss cheese also works, though it will taste milder. For a sharper topping, mix Gruyère with a little grated Parmesan; use a light hand, since Parmesan can make the toast saltier.

Skip the wine: Use an equal amount of broth to deglaze the pot. A teaspoon of cider vinegar stirred in with the broth can add a gentle acidic note, but it is optional and will make the soup taste a little brighter rather than wine-like.

Make it gluten-free: Use a gluten-free baguette or sturdy gluten-free bread, and omit the flour. The soup will be less thick, but the slowly cooked onions still give it body. Check that the broth is labeled gluten-free, too.

Storage and Reheating

For best texture, store the soup and cheese toasts separately. Transfer leftover soup to a covered container and refrigerate it within 2 hours of cooking; it keeps for 3–4 days. Cool it in a shallow container if you have a large amount, rather than leaving a full, hot tureen on the counter. Do not refrigerate the soup in a decorative tureen unless its maker says it is suitable for refrigerator use.

Reheat only the amount you plan to eat in a saucepan over medium heat, stirring occasionally until steaming hot throughout. For food-safety guidance, leftovers should reach 165°F (74°C); check with a food thermometer. Add a splash of broth or water if the soup has thickened in the refrigerator. Re-crisp leftover bread in a toaster oven or under the broiler, then top it with cheese and melt it shortly before serving. Freeze soup without the bread for up to 3 months; thaw it in the refrigerator overnight and reheat as above. The onions may soften further after freezing, but the flavor remains suitable for soup.

Frequently Asked Questions

Can I make French onion soup ahead?
Yes. Cook the soup through the simmering step, cool it promptly, and refrigerate it for up to 3–4 days. Reheat it in a saucepan before serving, and make the cheese toasts fresh so they stay crisp. If you plan to serve from a tureen, warm the vessel just before filling it.

Is a French soup tureen oven-safe?
Not necessarily. A tureen is a serving vessel, and its material, glaze, handles, and age determine whether it can tolerate oven or broiler heat. Unless the maker clearly labels it oven-safe, keep it away from the broiler and serve the soup with separately broiled cheese toasts.

Can I use sweet onions instead of yellow onions?
Yes, but the result may taste sweeter and can brown differently. Yellow onions are a balanced choice for this savory broth. If using sweet onions, omit the optional sugar, cook them gently, and taste the soup before deciding whether it needs a little more pepper or a splash of vinegar.

Why are my onions taking so long to brown?
Onions contain a lot of water, so they soften and release moisture before they begin to color. Keep the heat at medium-low once they have softened, stir regularly, and allow the full cooking time. A crowded or narrow pot can slow browning, but raising the heat too much risks burning the bottom.

What can I use if I cannot find Gruyère?
Comté, Emmental, or Swiss cheese are practical substitutes. Gruyère has a nutty, savory flavor and melts smoothly; Emmental and Swiss are generally milder. Choose a cheese that melts well, grate it yourself if possible, and broil the toasts only until the cheese bubbles.

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