French Onion Soup
This classic French onion soup builds its deep flavor slowly, with caramelized onions, savory broth, toasted bread, and melted Gruyère. It takes a little patience, but the method is simple and well worth the time at the‑
Total
105 min
Servings
4 to 6 servings
Level
Medium
French onion soup is a cozy, old-fashioned dish with a smart trick at its center: cook a lot of onions slowly until they turn sweet, soft, and golden brown. That slow cooking gives the soup its rich color and flavor without needing many ingredients.
The soup is finished with toasted bread and cheese, then broiled until bubbly. Use oven-safe bowls if you have them. If not, you can melt the cheese on the toasts separately and float them on top.
This recipe uses beef stock for a traditional savory base, plus a splash of wine to lift the flavor. If you prefer not to cook with wine, there is an easy swap in the tips.
01What you'll need
Ingredients
16 items · 4 to 6 servings
- 3 tablespoons unsalted butter
- 1 tablespoon olive oil
- 3 pounds yellow onions, halved and thinly sliced
- 1 teaspoon kosher salt, plus more to taste
- 1/2 teaspoon black pepper
- 2 teaspoons sugar, optional, to help browning
- 2 garlic cloves, finely chopped
- 1 tablespoon all-purpose flour
- 1/2 cup dry white wine, such as Sauvignon Blanc, or dry vermouth
- 6 cups low-sodium beef stock
- 2 sprigs fresh thyme, or 1/2 teaspoon dried thyme
- 1 bay leaf
- 1 teaspoon Worcestershire sauce, optional
- 1 small baguette, cut into 1/2-inch slices
- 1 1/2 cups grated Gruyère cheese
- 1/2 cup grated Parmesan cheese
02How to make it
Step-by-step
1. Slice the onions
Halve the onions from root to tip, peel them, then slice them thinly. Try to keep the slices about the same size so they cook evenly. A sharp knife makes this easier and safer.
2. Start the onions
Melt the butter with the olive oil in a large heavy pot or Dutch oven over medium heat. Add the onions, salt, pepper, and sugar if using. Stir well so the onions are coated in the fat.
3. Caramelize slowly
Cook the onions for 40 to 55 minutes, stirring every few minutes. Lower the heat if they start to burn. They should shrink a lot and turn soft, jammy, and deep golden brown. This step creates most of the soup’s flavor.
4. Add garlic and flour
Stir in the garlic and cook for 1 minute. Sprinkle in the flour and stir for another minute. The flour helps give the broth a little body, so it feels slightly silky instead of watery.
5. Deglaze the pot
Pour in the wine and scrape the bottom of the pot with a wooden spoon. This is called deglazing, which means loosening the browned bits stuck to the pan. Let the wine bubble for 2 to 3 minutes, until it reduces slightly.
6. Simmer the soup
Add the beef stock, thyme, bay leaf, and Worcestershire sauce if using. Bring to a gentle boil, then reduce the heat and simmer uncovered for 25 to 30 minutes. Taste and add more salt or pepper if needed. Remove the thyme sprigs and bay leaf.
7. Toast the bread
While the soup simmers, heat the oven to 400°F. Arrange the baguette slices on a baking sheet and toast for 8 to 10 minutes, turning once, until dry and lightly crisp. Toasted bread holds up better in the soup.
8. Broil with cheese
Switch the oven to broil. Ladle the hot soup into oven-safe bowls set on a baking sheet. Top each bowl with 1 or 2 toasted baguette slices, then sprinkle with Gruyère and Parmesan. Broil for 2 to 4 minutes, watching closely, until the cheese is melted and browned in spots.
9. Serve carefully
Let the bowls sit for 2 minutes before serving. The soup and bowls will be very hot. If you do not have oven-safe bowls, broil the cheese-topped toasts on a baking sheet, then place them on each bowl of soup.
03From our kitchen
Cook's tips
- Make-ahead: The soup base can be made up to 3 days ahead. Cool it, cover it, and refrigerate it without the bread and cheese. Reheat gently on the stove before serving.
- Storage: Store leftover soup without toppings in an airtight container in the refrigerator for up to 4 days. The bread topping is best made fresh.
- Freezing: Freeze the soup base for up to 3 months. Thaw overnight in the refrigerator, then reheat and add fresh toasted bread and cheese.
- No wine: Replace the wine with 1/2 cup extra beef stock plus 1 teaspoon red wine vinegar or sherry vinegar. Add the vinegar after the soup simmers so the flavor stays bright.
- Stock swap: Beef stock gives the classic flavor, but a good vegetable stock works for a vegetarian version. Use vegetarian Worcestershire sauce or leave it out.
- Cheese options: Gruyère melts well and has a nutty flavor. Swiss cheese, Comté, or fontina can work if that is what you have. Avoid pre-shredded cheese if possible, as it may not melt as smoothly.
Cook's note
Use a wide, heavy pot if you can. More surface area helps the onions cook evenly and caramelize without steaming too much. Do not rush them over high heat; burnt onions will make the soup taste bitter.
04Frequently asked
Questions & answers
Why are my onions not turning brown?
They may be crowded, too wet, or cooking over heat that is too low. Keep cooking and stir often. If there is a lot of liquid in the pot, raise the heat slightly for a few minutes to help it evaporate.
Can I use red onions or sweet onions?
Yes, but the flavor will change. Yellow onions are balanced and traditional. Sweet onions make a milder, sweeter soup, while red onions can give a slightly different color and sharper taste.
Do I need oven-safe bowls?
No. They are helpful for the classic melted cheese top, but not required. Broil the cheese on the toasted bread separately, then place the cheesy toasts on top of the hot soup.
How dark should the onions be?
Aim for deep golden brown, not black. A few darker edges are fine, but if the onions smell burnt or look black in spots, lower the heat and stir more often.
Can I make French onion soup vegetarian?
Yes. Use a full-flavored vegetable stock, skip the Worcestershire sauce unless it is vegetarian, and season carefully with salt and pepper. A small splash of soy sauce can add savory depth.
05Keep cooking
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