What Makes Onion Soup Different From French Onion Soup?
The beautiful thing about French onion soup is that while it looks complicated — mostly in its presentation — it's actually quite simple to make. A few key ingredients give it its characteristically rich flavor and while there aren't a lot of fancy cooking techniques required for making this dish, it does require some patience.
It's not a quick task to caramelize onions to perfection, it can take about an hour according to Martha Stewart's caramelized onion soup recipe. While an hour may seem excessive, Food 52 did an onion experiment where they caramelized the vegetable for 15, 30, and 60 minutes and found the onions that cooked the longest had the best flavor and texture. French onion soup is certainly a labor of love, and there's a window the onions need to stay within for them to play their proper role in the soup.
Cook them for too short a time and they are missing that rich, sweet flavor; cook them for too long and they burn. The proper technique requires standing at the stove, stirring, and monitoring in order to achieve the desired result but it's well worth it (via Martha Stewart). But what makes it French onion soup as opposed to onion soup?
Not just any old onion will do
French onion soup is a simple combination of caramelized onions, flour, butter, beef stock, and a bit of wine topped with a cheese toast (per The New York Times). While these ingredients are available in France, none of them are uniquely French, so what gives?
In comparing recipes for French onion soup and other onion soups, there are a few important things to note. The first of which is the type of onions you are using. Jamie Oliver's recipe for onion soup calls for multiple types of onions, including red onions, white onions, and leeks, while BBC Good Food does not denote a specific type of onion in its recipe for British onion soup.
When looking at French onion soup specifically, Food.com notes that Julia Child's classic French onion soup calls only for yellow onions. Who better to know the ins and outs of French cooking than the one who mastered it herself?
Different types of onions have distinct flavor characteristics. Yellow onions tend to be sweeter and All Recipes notes that they are perfect for caramelizing. White onions tend to be mild and red onions tend to be on the spicy side, so a yellow onion is a perfect choice for this rich soup with a touch of sweetness.
The stock you use matters
When it comes time to add liquid to the onions, both Julia Child's French onion soup recipe and Megan Miller of How To Cook.Recipes note that you should use beef stock to follow the classic recipe.
On the other side of the coin, BBC Good Food's recipe for onion soup calls for vegetable or chicken broth, while Jamie Oliver's recipe offers a dealer's choice suggestion of beef, chicken, or vegetable broth depending on which you like best. It should also be noted that Julia Child's recipe does not call for any additional aromatics or herbs, while Oliver's includes shallots, sage, garlic, and Worcestershire sauce. Most French onion soup is topped with a Gruyère cheese crostini, while Oliver's recipe calls for cheddar.
In summary, general onion soup recipes are seemingly more complicated, and the simpler French recipe sticks to classic flavors and doesn't allow much wiggle room for creativity. Whichever one you choose to make, don't forget to have a box of tissues handy for those onion tears.