French Onion Soup
Deeply caramelized onions in a rich broth under a crust of bread and cheese.
- Preparation
- 20 min
- Cook/bake time
- 1 hr 10 min
- Total
- 1 hr 30 min
- Difficulty
- Medium
- Calories
- 708 kcal
- Servings
- 4
- Prep
- 20 min
- Cooking & baking
- 1 hr 10 min
Deeply caramelized onions in a rich broth under a crust of bread and cheese. The onions truly need forty minutes to go from translucent to deep brown, and this time is exactly where all the flavor of the soup comes from. There are no shortcuts here, but the result justifies every bit of effort.
Why this works
Onions consist of about nine percent sugar, which is more than most vegetables. During caramelization, the cellular water must first evaporate, and then the sugars and amino acids begin to react with each other, which is exactly what creates the dark, sweet and savory flavors. This is a process of time, not a process of heat. At high temperatures, the edges burn before the center has even lost water. That is why there is no shortcut here.
Step-by-step instructions
- 1
Start the onions
Melt the butter and olive oil in a large, heavy pot and add the onion rings with salt and sugar. Cover the pot and let them sweat over medium heat for ten minutes until they collapse and release liquid. The salt draws out water, and the sugar supports the caramelization later.
- 2
Caramelize
Remove the lid and let the onions cook uncovered for forty minutes over medium to low heat. Stir every few minutes and scrape off the brown bits from the bottom, because that is where the flavor sits. They are done when they are deep brown, syrupy and significantly shrunken. This time is non-negotiable.
- 3
Flour and wine
Sprinkle the flour over the onions and stir it in for two minutes so it toasts slightly and thickens the soup later. Pour in the white wine and scrape all the browned bits off the bottom with a wooden spoon. Let the wine reduce for two minutes until the smell of alcohol has disappeared.
- 4
Simmer the soup
Pour in the broth and add the bay leaves and thyme. Let the soup simmer uncovered over low heat for twenty minutes so it gains depth and reduces slightly. Remove the herbs, stir in the Cognac and season to taste with salt and pepper.
- 5
Bake
Ladle the soup into ovenproof bowls, place two toasted baguette slices on top of each and pile the grated Gruyère over them until it touches the rim. Place the bowls under the oven broiler and bake them for five to seven minutes until the cheese is bubbling and has dark spots. Serve immediately, but carefully, as it is very hot.
Our best tips
- Forty minutes of caramelization is the entire recipe. If you stop after fifteen minutes, you get onion broth instead of onion soup.
- A heavy pot with a thick bottom prevents the onions from burning instead of caramelizing.
- The cheese should touch the rim of the bowl, as this seals the soup and forms the typical crust.
Tasty variations
Vegetarian
Use a rich vegetable broth with a teaspoon of miso paste, which replaces the depth of the beef broth surprisingly well.
Without an oven
Bake the cheese baguette separately in the oven and only place it on the soup once it is in the bowl.
Nutrition facts
| Calories | 708 kcal |
|---|---|
| Protein | 23 g |
| Carbohydrates | 60 g |
| – of which sugar | 21 g |
| Fat | 35 g |
| Fiber | 7 g |
Where the 708 kcal come from
per serving
Calculated from the ingredients – how we do it
We add up reference values for every ingredient and divide by the number of servings. These assumptions are baked in:
- Reference values per 100 g – for the raw ingredient, exactly as listed.
- Tinned goods count at drained weight, bone-in meat at purchase weight: you eat about 70 per cent of a chicken thigh and leave the rest.
- Water evaporates as you cook. The energy stays in the pot, the weight does not – so the figure is per serving, not per 100 g of finished dish.
- Anything listed without a quantity – “salt and pepper” – is not counted.
A guide value, not a lab measurement: no two onions weigh the same, and fat content varies from pack to pack.
Frequently asked questions
Can I shorten the caramelization time?
Only to a limited extent. A little baking soda speeds up the process but changes the texture. Forty minutes is the honest answer.
Which onions are suitable?
Normal yellow onions are ideal because they contain enough sugar. Red onions turn mushy, and sweet onions are too watery.
Can I prepare the soup in advance?
Very well. The soup without the cheese crust keeps for three days and tastes better reheated. The baking is only done right before serving.
Comments & ratings(0)
Sign in to rate and comment on this recipe.
You might also like
DinnerGratin Dauphinois
Potato gratin without cheese and without egg: just potatoes, cream, garlic, and nutmeg, exactly as it should be in the Dauphiné region.
DinnerCassoulet
Bean stew from the Languedoc with duck, sausage, and pork, and the crust that is pushed down seven times.
Soups & StewsPotato Leek Soup
Velvety soup made from just a few ingredients, served with croutons and chives.