This recipe for French Onion Soup reveals clever tips and substitution options to make your own, heart-warming version of the classic comfort dish. Includes vegan option.
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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.
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 foundation of the soup and creates the sweet, enticing, deep flavors of the dish. Much as you must take your time while eating a bowl of French onion soup in order to fully appreciate it, you can’t rush the onion caramelization process.
During the first 30 minutes, the sliced onions will release their water, which will reduce their volume considerably and make them tender. When 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 or so. 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.
After the caramelization is done, 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 (also called Spanish onions) are the usual go-to variety for this soup, but I like to mix 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 chemical 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 cannot just 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 period of time and slicing them right as they come out of the fridge can help you shed less tears. (Note that you should not store onions in the fridge for extended periods of time, because refrigeration keeps the moisture in, which makes onions go bad more quickly.)
Use a very sharp knife: Sharp knives cut onions more cleanly, which reduces the amount of irritants that are 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, which will lead to fewer tears.
Wear goggles: I’m not gonna lie, I wear ski goggles when I slice onions for making French onion soup. It may not be a pretty sight, but it works! You can even buy “onion goggles,” which are 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: My favorite alcohol to use in French onion soup 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. If you want to switch things up, however, you can use a full-bodied red wine or even a dark beer. Traditionally, fortified wines such as Madeira, sherry, or port are used. Whatever you use, know that the alcohol content will evaporate fully during the simmering process, making the soup safe to serve to children. Even so, if you prefer, you can feel free to skip adding alcohol completely.
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, because this makes 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 I distribute them over servings. This makes them sturdier, which means they keep their shape and texture better after the cheese broiling process.
Make it vegan: French onion soup is just a couple ingredients short of being a vegan dish. See my instructions to make Vegan French Onion Soup in the recipe below.
Cubed crustyday-old bread or baguette, preferably sourdough—about 1/2 cup / 125 ml per serving
Shredded ComtéGruyère, Emmenthal, Swiss, or Old Cheddar Cheese—a generous 1/4 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.
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