The short answer: French onion soup is a rich beef broth full of slowly caramelized onions, served under a slice of toasted bread and melted Gruyère. **Cook 3 pounds of thinly sliced yellow onions in 4 tablespoons of butter over medium-low heat for 45 to 60 minutes, stirring every few minutes, until they're deep brown.
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Prep time: 20 minCook time: 1 hr 34 minTotal time: 1 hr 54 minServings: 6 servings
Add ½ cup of dry white wine or sherry, 8 cups of beef broth, a few thyme sprigs and a bay leaf, and simmer 20 minutes. Ladle into oven-safe bowls, top with toasted baguette and shredded Gruyère, and broil 2 to 4 minutes until bubbling.** It serves 6. The only real secret is patience with the onions, and below is how to get them right, plus swaps, a slow cooker method and freezing.
I love cooking, and I especially love cozy fall and winter dinners. This soup tastes like it took all day, but most of that time is the onions doing their own work.
French onion soup ingredients
| Ingredient | Amount | Note or swap |
|---|---|---|
| Yellow onions | 3 pounds (about 6 large) | Up to 1 sweet or red onion in the mix |
| Butter | 4 tablespoons | Half olive oil |
| Salt | 1 teaspoon, plus to taste | Helps the onions release moisture |
| Sugar | ½ teaspoon (optional) | Speeds browning a little |
| Garlic | 2 cloves, minced | |
| Flour | 1 tablespoon | Thickens slightly; skip for gluten-free |
| Dry white wine or dry sherry | ½ cup | Broth plus 1 tablespoon vinegar |
| Beef broth, low sodium | 8 cups | Half chicken broth for a lighter soup |
| Fresh thyme | 4 sprigs | ½ teaspoon dried |
| Bay leaf | 1 | |
| Baguette | 6 slices, ¾ inch thick | Day-old is best |
| Gruyère | 2 cups, shredded | Swiss, Comté or provolone |
How to make French onion soup, step by step
- Slice the onions. Halve them root to tip and slice them about ¼ inch thick so they cook evenly.
- Start the onions. Melt the butter in a large Dutch oven over medium heat, add the onions and salt, and stir to coat. They'll fill the pot, then cook down by more than half.
- Caramelize slowly. Cook 45 to 60 minutes, stirring every 5 minutes and lowering the heat if they brown too fast. If brown bits stick, add 2 tablespoons of water and scrape them up. Stop when they're the color of strong tea.
- Season. Add the garlic for 1 minute, then stir in the flour for 1 minute more.
- Deglaze. Pour in the wine and scrape the bottom of the pot until it's clean.
- Simmer. Add the broth, thyme and bay leaf and simmer 20 to 30 minutes. Taste and add salt and pepper.
- Toast and top. Toast the baguette slices. Set oven-safe bowls on a sheet pan, fill them with soup, float a toast on each and pile on the cheese.
- Broil. Broil 6 inches from the heat for 2 to 4 minutes until browned and bubbling. The bowls will be very hot, so serve them on plates.
Onion color and flavor, minute by minute
| Time | Color | Flavor |
|---|---|---|
| 10 minutes | Soft and pale | Mild, still sharp |
| 25 minutes | Light gold | Sweet |
| 45 minutes | Amber | Rich and sweet |
| 60 minutes | Deep brown | Jammy, the classic soup flavor |
Shortcuts that still work
- Make the onions ahead. Caramelized onions keep 4 days in the fridge, so a weekend batch makes a weeknight soup take 30 minutes.
- Slow cooker onions. Cook the onions with butter and salt on high for 8 to 10 hours with the lid slightly open. The USDA's slow cooker safety page covers filling and temperature basics.
- No oven-safe bowls. Broil cheese toasts on a sheet pan and set one on each bowl.
- Vegetarian. Use a rich mushroom or vegetable broth and add 1 teaspoon of soy sauce for depth.
Looking for more cozy bowls? Browse all our soup recipes, or try a creamy potato soup.
Storing and freezing
Store the soup and the bread separately. The USDA's leftovers guidance says to refrigerate cooked food within 2 hours, and FoodSafety.gov's cold storage chart gives soups 3 to 4 days in the fridge and 2 to 3 months in the freezer. Add fresh toast and cheese each time you reheat.
Plan soup night
Yellow onions, broth and a little cheese are inexpensive staples, so French onion soup feels special without a special grocery bill, especially once it has a regular spot on the plan.
- Meal Planner & Grocery List, $3.99. Put the weekend onion prep and the weeknight soup on one plan, and shop from one list.
- Family Recipe Binder, $6.99. Write down your timing and cheese mix on a recipe card so the next pot is just as good.
- Holiday Season Bundle, $15.99 (regularly $25.94 for the six items bought separately). The meal planner plus the Christmas Budget & Gift Planner, a cleaning schedule and savings trackers.
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The soup depends on a deep, jammy base. Our guide to how to caramelize onions shows the 30 to 45 minute stovetop method and the stages to look for.
Frequently asked questions
How do you make French onion soup? To make French onion soup, slowly cook 3 pounds of thinly sliced yellow onions in 4 tablespoons of butter for 45 to 60 minutes until deep brown, deglaze with ½ cup of dry white wine or sherry, then simmer with 8 cups of beef broth, thyme and a bay leaf for 20 minutes. Ladle it into oven-safe bowls, top with toasted baguette and Gruyère, and broil until bubbly.
How long does it take to caramelize onions for French onion soup? Caramelizing onions for French onion soup takes 45 to 60 minutes over medium to medium-low heat. Recipes that promise 10 minutes only soften and lightly brown the onions; the deep, sweet flavor needs the full time.
What are the best onions for French onion soup? Yellow onions are the best onions for French onion soup because they balance sweetness and bite. You can mix in one sweet onion or a red onion, but all-sweet onions can make the soup taste flat.
What cheese goes on French onion soup? Gruyère is the classic cheese for French onion soup because it melts smoothly and browns well. Swiss, Comté or a mix of Gruyère and provolone also work, with a little Parmesan on top for extra browning.
What can I use instead of wine in French onion soup? Use an extra ½ cup of broth plus 1 tablespoon of apple cider vinegar or balsamic vinegar instead of wine. The acid brightens the soup the same way wine does.
Can you make French onion soup without oven-safe bowls? Yes, make cheesy toasts separately: top baguette slices with Gruyère on a sheet pan, broil until bubbly and float one on each bowl of soup. You get the same melted top with any bowl.
Can you make French onion soup in a slow cooker? Yes, put the sliced onions, butter and a pinch of salt in a slow cooker on high for 8 to 10 hours with the lid slightly open to caramelize them. Then add the broth and wine and cook on low 1 to 2 hours before topping and broiling.
Can you freeze French onion soup? Yes, French onion soup freezes well for 2 to 3 months without the bread and cheese. Thaw it in the fridge, reheat it on the stove, then add fresh toast and cheese and broil.
How long does French onion soup last in the fridge? French onion soup lasts 3 to 4 days in the fridge. Store the soup without the bread so the toast doesn't go soggy, and refrigerate it within 2 hours of cooking.
Why is my French onion soup bitter? French onion soup turns bitter when the onions scorch instead of caramelizing slowly. Keep the heat at medium-low, stir every few minutes, and add a splash of water to loosen any dark spots before they burn.
What bread is best for French onion soup? A sturdy baguette or country loaf is best for French onion soup. Slice it about ¾ inch thick and toast it until dry and crisp so it holds up under the cheese instead of dissolving into the broth.
How do I make soup night easy to plan? Caramelize the onions on a weekend and plan soup for a weeknight. The Meal Planner & Grocery List from HomeBase Paper Co. ($3.99) holds the weekend prep step, soup night and the grocery list on one page.
Sources
- USDA FSIS: Leftovers and food safety fsis.usda.gov
- FoodSafety.gov: Cold food storage chart foodsafety.gov
- USDA FSIS: Slow cookers and food safety fsis.usda.gov