French Onion Soup

French Onion Soup is a classic rustic French soup perfect for a cold winter’s day. Done properly, start to finish, this soup can take up to 48 hours, so most people are very intimidated by it. But since most of that work is passive, this is actually a very simple recipe that every home cook should know.
Onion soup is so time-consuming because of the soup base, namely, a beef stock. Beef stock is made with beef bones and, at the lowest of simmers, takes anywhere from 16 to 48 hours of stove time. I have a chicken stock recipe already uploaded, and you can find that by clicking here. The process for beef stock is nearly the same: roast the bones and the aromatics, add a lot of water to a tall pot with as much volume as possible, and let it simmer as gently as possible for as long as possible. If you want, you also have the option of following the stock recipe exactly by using chicken wings to make chicken stock, even though the traditional version of the soup uses beef stock. If you are vegetarian/vegan, I suppose you could make this soup entirely vegan by roasting vegetables and mushrooms, adding water and soy sauce, and simmering that to make a vegetable stock to serve as a base.
 

Cut 3 pounds of yellow onions in half pole-to-pole, that is, through the root and the stem ends, like I always recommend for when they are to be chopped. Peel the onion halves, and then cut them thinly, once again pole-to-pole. If you have a mandolin slicer, use it, but be sure to put on a hand guard first, since mandolin blades can be very sharp. If you use a knife, make sure your blade is sharp, not only because sharper blades are safer, but also because sharper blades disturb fewer cell walls and are thus less likely to make you or anyone else around you cry as you slice the onions. Once all the onions have been sliced, melt a whole stick of butter. Once the butter has melted but has not started browning, place all the onions into a large pan or Dutch oven.

Caramelize the onions slowly, over medium-low heat. Stir constantly. Caramelization is not a linear process, so you should never step away from caramelizing onions. Watch and stir them constantly from anywhere between 30 and 60 minutes, depending on how much moisture your onions need to expel before they start taking on color.

If you have any, when the onions are almost done, you can deglaze the pan with sherry or cognac. Otherwise, use an equivalent amount of water (2-3 ounces) to deglaze the pan. The caramelization process certainly created fond—the chef’s dream, the sticky flavorful bits that get stuck to cooking surfaces, just waiting to be dissolved. Deglazing a cooking surface picks up that fond with a liquid and dissolves the fond into that liquid, so no flavor is lost. The onions have finished caramelizing when they are deep mahogany brown, have an almost jammy consistency, and are about to burn but have not yet. Monitoring the onions as they get closer and closer to this point is essential. I’ve said it already, but it is worth repeating you CANNOT walk away from caramelizing onions, or they will burn.

For 3 pounds of onions, I recommend about half a gallon of stock. Add the stock to the onions, and let simmer, stirring occasionally for 25 minutes. Once the stock goes in, you can afford to step away, only checking every five minutes or so. There’s a gallon of liquid in your pan/Dutch oven, so surely nothing will burn because there’s no way that a gallon of liquid will evaporate, since the liquid is only simmering, and for not even half an hour. Check for seasoning and adjust as normal, bearing in mind that my stock recipe never called for salt precisely so that at a moment like this, you could season your soup to your liking.

In the meantime, figure out how many portions of soup you will be serving right away (this soup is great for leftovers after the fact, but right now, handle however many people you’ll be feeding right away). Find that many oven-safe ramekins or bowls and cut slices of baguettes about ¾ of an inch thick so that the tops of all those dishes can be covered in bread. At the same time, grate enough Gruyere to generously cover all of the bread.

When 25 minutes have elapsed, the soup is ready to be portioned into the ramekins. Top the soup with the bread, and then top the bread with the cheese. Place the filled ramekins on top of a baking sheet and place the baking sheet into an oven with the broiler (“grill” if you speak non-American English) on high. Check on the soup after 90 seconds, and every 15 seconds thereafter. The objective is for the cheese to take on some “leoparding,” that is, for it to look like the cheese on top of a well-made cheese pizza: taking on some color but not burned. Once you are satisfied with the degree of melting and leoparding of the cheese, turn off the broiler, carefully remove the ramekins from the oven and serve.

(Credit: Wikimedia Commons)