French onion soup is commonly found on restaurant menus all over the country. Whether in a roadside diner or fine dining establishment, it is not uncommon to find a hot and hearty variation of this classic soup being served.
There are varying stories on the origin of French onion soup, though most tales trace it back to 18th-century France. The recipe similar to that which is still made today began showing up in French cookbooks in the early 1700s. The first published recipes are based on the modern French bouillon recipe that was refined during the 17th century. French onion soup gained popularity in the United States during the 1960s when French cooking was highly promoted by chefs like Julia Child.
The main ingredients in French onion soup are onions, butter, beef broth, sliced French bread and Swiss or Gruyere cheese. All of these ingredients are found in any recipe for a traditional french onion soup. Most recipes for the soup also include varying amounts of other ingredients like sugar, garlic, white wine, sherry or thyme.
Cooking french onion soup requires several steps. Not all recipes call for the same steps in the same order, but the process is generally very similar. First, the onions are caramelized. Caramelizing the onions releases the rich flavor that is responsible for giving the soup its intense taste. After caramelizing the onions, most recipes instruct the cook to de-glaze that pan in which the onions were caramelized. Broth and any additional seasoning that the recipe calls for are then added to the pan. After the mixture has simmered for the required amount of time, the soup is poured into individual bowls, topped with a slice of French bread and then with a layer of Swiss or Gruyere cheese. Individual bowls are then placed under a broiler to toast the bread and melt the cheese.
Traditional French onion soups are served in individual bowls with a thick crust of melted cheese and toasted bread on the top of the bowl. Since this crust of cheese and bread is achieved by placing the individual serving of soup under a broiler, French onion soup is often served in small ovenproof crocks or ramekins.
Though onions themselves are low in calories, French onion soup can be high in calories and fat. Since most recipes call for the onions to be caramelized in butter or olive oil, that fat remains with the onions in the soup. The cheese and bread crust also add fat, carbohydrates and calories to the dish.