French onion soup (soupe à l’oignon) is a classic all time favorite around the world, especially with the growing interest in French cuisine. Traditionally, it was served as an early morning meal to the porters and workers of Les Halles market in Paris, originating in France during the 18th century. Ancient in origin, French onion soup is perhaps the most famous of soups with its distinctive dark color topped with the French baguette crouton.
Although the French onion soup recipe is misleadingly simple with only 4 main ingredients (onions, broth, croutons, and cheese), the whole process takes many hours including the time needed to make the best homemade stock. The rich flavour of the soup base comes from the infusion of the best homemade broth and the plentiful caramelized onions. The long slow cooking of the onions is the key to success while making great French Onion soup. This slow cooking procedure is known as sweating the onions in fats such as butter and olive oil to draw out the liquid during the process of caramelization. Salting the onions and cooking them slowly, covered, over low heat serves to draw the liquid out of the onions to achieve that distinctive straw yellow color. If the onions brown too quickly the soup will be bitter. In the final stages of caramelization, the pot is deglazed with wine or liquor to enhance the flavour. Hence using a stainless steel pot is important to allow for this deglazing process.
Traditionally, French onion soup is made from beef broth, but modern variations include substituting with chicken stock which makes a lighter colored broth. Other modern variations to the French onion soup recipe include the addition of a bouquet garni of parsley, thyme and a bay leaf; and also the addition of red wine. I have chosen to use red wine vinegar in my French onion soup recipe, along with other variations to give it a tasteful twist.
The soup base is usually topped with a French baguette crouton, with must be toasted dry and crusty to allow it to float on the surface of the soup while broiled with cheese on top. Gruyère cheese is usually the cheese of choice, although I have seen some use Swiss cheese or white cheddar. I prefer broiling the soup in a large ramekin and serving it right from oven to table. However, it is also acceptable to bake the finished soup at high oven temperature (425oF) until the cheese melts.
I’ve made this French onion soup several times and perfected it with the use of my homemade chicken stock recipe in combination with flavoring the croutons with fresh garlic and mustard after toasting. My French onion soup recipe makes about 6 servings and tastes better and better with each day stored in the refrigerator and simmered again the next day! All in all this recipe took me 2 days of work including the homemade chicken stock recipe, but it was worth every minute. I truly enjoy watching my guests slurp up every last drop!
1/4 cup (4 tbsp) butter
1 tbsp olive oil
4 lbs (about 8 medium) yellow onions and sweet onions
Kosher salt and black pepper to taste
1 tsp chopped fresh thyme leaves
1 tsp castor sugar
1 tbsp red wine vinegar
3/4 cup dry white wine, such as Sauvignon Blanc
3 tbsp brandy
7 cups homemade chicken stock
1 1/2 tbsp all-purpose flour
1 sprig parsley
1 bay leaf
For the croutes
1 French baguette, cut into 1 inch thick slices at a slight diagonal
1 garlic clove, halved
1 tbsp Dijon mustard
1 cup coarsely grated Gruyère cheese
Cut the onions in half lengthwise (from top to root) and peel the onions. Thinly slice the onions. Set aside.
Melt the butter with the oil in a large stainless steel pot (at least 8 quart) over medium heat. Add the onions and stir to coat them in the oils. Season the onions lightly with salt and pepper. Cook over medium heat for 5 minutes, stirring once or twice, until the onions just begin to soften.
Stir in the thyme.
Reduce the heat to low, cover the pot and cook the onions until they are very soft and turn a dark straw yellow color, stirring frequently. This will take about 45 minutes to an hour.
Uncover the pan and increase the heat to medium-low. Stir in the sugar and cook for 5 minutes until the onions start to brown. Add the sherry vinegar and increase the heat again to medium, then continue to cook while stirring frequently until the onions turn a deep golden brown (about 20 minutes).
Meanwhile, bring the homemade chicken stock to a boil in another pot, and then keep to a gentle simmer.
Stir the flour into the onions and cook for about 2 more minutes.
Pour in the wine and the brandy, and increase the heat to medium-high, stirring and scarping to loosen any caramelized juices until the liquid is mostly reduced (about 5 minutes).
Add the hot chicken broth, toss in the parsley and bay leaf, and season the soup to taste with salt and pepper. Simmer on medium-low heat for 20 minutes to infuse the broth with the onion flavor. The onions should be soft but not falling apart at this time. Remove the parsley and bay leaf.
To make ahead: the soup can be made ahead to this point and then cooled and refrigerated for a few days.
To prepare the croutes, preheat the oven to 300oF. Place the slices of baguette onto a greased baking tray and bake for 15 minutes until dry and lightly browned.
Rub the bread with cut surface of the garlic halves and spread with some mustard.
Preheat the oven’s broiler on the hottest setting. If the soup was made ahead and refrigerated, bring the soup back to a simmer. Set 6 ovenproof soup crocks or ramekins on a heavy rimmed baking sheet lined with aluminum foil and ladle the soup into the crocks. Float the prepared baguette slices on top, enough to cover the soup surface without too much overlap.
Top the bread with the grated Gruyère cheese, and then broil until the cheese melts and bubbles and begins to brown in spots. Serve immediately.