This French Onion Soup recipe reveals tips to make a heart-warming version of the classic comfort dish at home. Includes vegan variation.
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What do you associate with French onion soup—warming up after playing outside in the winter, spending a romantic night out with your special someone, savoring the classic dish during a trip to France? Whatever your mind drifts to when you think of French onion soup, I’m sure it’s heart-warming thoughts. I can hardly think of any other soup that so comforting, hearty, and satisfying to eat.
What is French Onion Soup Exactly?
Onion soups have been around for hundreds of years. Since onions have always been plentiful, cheap vegetables, they’ve always been the basis for nutritious soups everyone could afford to make and eat. For a long time though, onion soup was considered as “peasant food” and people in the upper classes were avoiding it. One of the first instances of a French onion soup recipe was published in an 18th-century cookbook and was called “peasant-style onion soup” (soupe à l’oignon à la Paysanne).
Today’s version of French onion soup—topped with croutons and melted cheese—appeared in Paris in the 18th century. It was served around Les Halles, the central market in Paris, and enjoyed as an affordable, hearty meal you’d get while shopping. Traditional restaurants around Les Halles–La Poule au Pot, Chez Baratte, Au Pied de Cochon– eventually started serving it, which contributed to it becoming a quintessential Parisian dish. All of these restaurants are still around today, and they still serve traditional French onion soup, hundreds of years later.
French Onion Soup at the restaurant Au pied de cochon, in Paris (photo credit: Au pied de cochon)
Here’s how to Make French Onion Soup
Classic French onion soup comes together in two main steps: the caramelization of the onions, and the simmering of the soup.
The first step—the caramelization of the onions—is the most important one. It’s the step that builds the soup’s foundation and creates the dish’s sweet, enticing, deep flavors. Much as you must take your time while eating a bowl of French onion soup to fully appreciate it, you can’t rush the onion caramelization process.
During the first 30 minutes, the sliced onions will release their water, reducing their volume considerably and making them tender. Once the excess water is evaporated, the caramelization process starts, and it needs to happen slowly but steadily. Keep the heat low throughout this process, and stir the onions every 5 minutes. This will prevent the onions from sticking to the bottom of the pot and allow them to cook slowly and evenly. The onions will gradually change color, first turning golden yellow and eventually golden brown. The caramelization process takes between 30 to 45 minutes, depending on the heat and the cooking pot you’re using. The onions don’t need to be very dark by the end of the cooking time, but they should be melty, translucent, and sweet.
Once you’re done with caramelizing the onions, it’s just a matter of stirring in the remaining ingredients and leaving the soup to simmer for an additional hour. The full process of making French onion soup thus takes about 2 hours, but it’s a mostly hands-off task. Plus, this recipe makes a big batch, and French onion soup freezes wonderfully, so your efforts will be rewarded for meals to come.
Helpful Tips for Making Classic French Onion Soup
Play with different onion varieties: Large yellow onions (Spanish onions) are the usual go-to variety for this soup, but I like mixing things up. Red onions are also a good pick. Sweet onions, such as the Walla Walla and Vidalia varieties, don’t have the sharp, piquant flavor of other varieties, which means they can add natural sweetness to French onion soup. Try swapping in sweet onions for one-third of the quantity required by the recipe, or use half yellow and half red onions. Mixing up the varieties of onions creates a lovely, complex, memorable soup.
Protect your eyes: The step I dread every time I make French onion soup is slicing the onions. My eyes are super sensitive to the chemicals released when slicing onions—I cry so much, and my eyes sting so badly that I go blind for a couple of minutes. Yet my love for French onion soup is so great that I can’t stop making it, so I had to find ways to get through the onion-slicing task. Here are my top tips to minimize the burning effect of slicing onions:
Refrigerate the onions for 30 minutes before slicing: Cold onions release less of their eye-tingling chemical, so refrigerating them for a short time and slicing them right as they come out of the fridge can help you shed fewer tears. (Note that you should not store onions in the fridge for extended periods because refrigeration keeps the moisture in, making onions go bad faster.)
Use a very sharp knife: Sharp knives cut onions more cleanly, reducing the amount of irritants released.
Slice the onions under a working vent hood: If your kitchen layout allows it, set your cutting board next to the stove and turn on the hood to the highest setting. Most of the chemical irritants will be pulled up into the vent hood and away from your eyes, leading to fewer tears.
Wear goggles: I’m not gonna lie, I wear ski goggles when I slice onions to make French onion soup. It may not be a pretty sight, but it works! You can even buy “onion goggles,” specially made for protecting your eyes when you slice onions. If you wear contact lenses, you’re in luck: the lenses will protect your eyes from being hit with the tear-jerking chemical contained in onions.
Switch up the alcohol you use—or skip it entirely: Traditionally, cognac, brandy, and cider are used in French onion soup, but my choice is a sharp, dry white wine, because I don’t like my soup to be too sweet. I find that wine balances out the sweetness and deepens the structural flavors of the soup. Fortified wines such as Madeira, sherry, and port are also used, or you could even switch things up and use a full-bodied red wine or even a dark beer. Whatever your choice, know that the alcohol content evaporates fully during the simmering process, making the soup safe to serve to children. Even so, if you prefer, you can skip adding alcohol completely and use extra chicken, beef, or vegetable stock instead.
Pick the right cheese: The cheese you use for topping French onion soup should be a sharp, flavorful variety. Nutty, aged Comté is my favorite cheese to melt over French onion soup, but Gruyère, Swiss, Emmenthal, and aged Cheddar are also great choices.
Cube and toast that bread for maximum satisfaction: The bread you use for topping French onion soup should be sturdy and crusty. Although slices of bread are often used to top onion soup, I much prefer slicing the bread into large cubes, making it much easier to fish out perfect bites when you eat the soup. (Try cutting off a bit of that cheesy bread slice without fully dunking it to the bottom of the soup! So frustrating!) I go the extra mile and toast the bread cubes before distributing them over servings. This makes them sturdier, which means they keep their shape and texture better after the cheese broiling process.
How to make vegan French Onion Soup
French onion soup is just a few ingredients short of being vegan. Here’s how to make vegan French onion soup.
Use extra-virgin olive oil to caramelize the onions instead of butter. You can also use vegan butter, if you prefer;
Use vegetable stock instead of chicken or beef stock;
½cupdry white wine, cider, amber or dark beer, or full-bodied red wine, or ¼ cup (60 ml) cognac, brandy, or fortified wine, such as Madeira, Sherry, or Port(if you don't want to use alcohol, substitute ½ cup/125 ml extra chicken or beef stock)
Crusty day-old bread or baguette, preferably sourdough, cut into large cubes—about ½ cup/125 ml per serving
Grated aged cheese, such as Comté, Gruyère, Emmenthal, Swiss, or Old Cheddar Cheese—a generous ¼ cup/60 ml per serving
Place a large stockpot or Dutch oven over medium-low heat. Melt the butter into the oil. Add the onions, sprinkle with the salt, and stir to coat with the butter and oil mixture. Cook the onions, stirring thoroughly using a wooden spoon every 5 to 10 minutes, for a total of about 1 hour, or until the onions and melty, sweet, and golden brown.
Pour the wine over the onions, then scrape the bottom of the pan to deglaze. Let the liquid evaporate almost completely, then sprinkle with the flour and stir to incorporate. Add the stock, mustard, and thyme (if using fresh thyme, no need to pick the leaves from the stems—simply add the whole sprigs to the pot). Stir to combine and season with black pepper. Increase the heat to bring the soup to a simmer. Half-cover, then lower the heat to keep the soup at a steady simmer. Cook for 45 minutes, stirring every 15 minutes. Taste the soup and add more salt if needed. Fish out the sprigs of fresh thyme, if needed.
SERVING: Set a rack in the middle position of the oven and turn the oven broiler on. (Setting the rack too close to the broiler will burn the bread and cheese too quickly.) Spread the bread cubes over a baking sheet. Toast for 2 minutes, then stir the cubes and return to toast for an additional 2 minutes (make sure to keep a close eye on the bread cubes to prevent them from burning.) Remove from the oven and set aside.
Place oven-proof bowls or crocks over a baking sheet then fill 3/4 of the way up with soup. Top each serving with about 1/2 cup (125 ml) toasted bread cubes and 1/4 cup (60 ml) shredded cheese. Transfer to the oven and broil until the cheese is melted, golden brown, and bubbly. Carefully transfer each bowl to a serving plate (the bowls are piping hot so setting them on a cool plate makes them easier to handle). Serve immediately.
STORAGE: Let the French onion soup cool to room temperature. Store in portions in airtight containers. Refrigerate for up to 3 days or freeze for up to 3 months.
HOW TO MAKE VEGAN FRENCH ONION SOUP: Substitute oil for the butter. Use vegetable stock instead of chicken or beef stock. Top the soup with a combination of shredded vegan cheeses, such as Daiya’s Mozzarella Style Shreds for meltiness combined with Follow Your Heart’s Vegan Parmesan Shredded Cheese Alternative for flavor.
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