It’s the middle of summer and over 90 degrees outside, but I had to make French Onion Soup as a prop for a photoshoot… And it was worth every drop of sweat. Sure, I could have mocked something up with watered down coffee, bread, and cheese, but a fake dish never looks quite as delicious as the real thing and I figured if I was going to take the time to fake something, I may as well take a little more time and do it right.
A good French Onion Soup (a.k.a. soupe à l’oignon gratinée) has a crisp layer of bread topped with a layer of crusty caramelized cheese. Poking a spoon through the crust reveals a deep-brown bottomless pit of flavor that hammers home the rich beefy stock made sweet and nutty from caramelized onions. Because there are so few ingredients, the trick is to get the onions caramelized all the way, and to use a good beef stock.
Onion Soup is such a simple dish, and yet it always amazes me how poorly most restaurants make it. There’s not much to it, but it does take a bit of time to make properly, so most restaurants cheat by adding too much sugar, excess salt, or MSG so they can get away with not caramelizing the onions all the way. These shortcuts result in a soup that’s too sweet, too salty, or unnervingly good tasting. Don’t get me wrong, I’m a big fan of saving time, but not at the expense of flavor.
To save a little time in my version of french onion soup (without giving up any flavor), I slice my onions very thin with a mandoline, then add salt and just a bit of sugar to speed up the process. For both caramelization and the Maillard reaction to take place, the onions need to get up above the boiling temperature of water. As long as the onions contain their natural moisture, they will not brown evenly. Slicing the onions thin, helps the water escape more quickly and evenly, and the salt draws the moisture out of the onions through osmosis.
Ideally you want to get the onions as brown as possible before adding the stock. The problem is that the browned bits stuck to the bottom of the pan will start burning before the onions reach their full potential, so I deglaze the pan once with sherry to slow down the reaction and to scrape the darkest bits off the bottom of the pan. This should get you a pot full of mahogany brown onions that are glistening with butter, and sticky from the concentration of caramelized sugar.
Since making stock from scratch would take all day, I start with a high quality packaged stock and add a spoonful of demi-glace (concentrated veal stock), to round out the flavor of the soup. Some might call this sacrilege, but the six hours saved is worth any minor degradation in flavor.
French Onion Soup
4 large yellow onions sliced very thin
4 tablespoons of butter
1 tablespoon Kosher salt
1 tablespoon sugar
1/4 cup dry sherry
1 quart good quality beef stock
1 tablespoon of demi-glace (optional)
1/2 teaspoon dried marjoram
1 bay leaf
salt to taste
8-12 slices of baguette sliced 1/2″ thick and lightly toasted
6 ounces grated Comté (a.k.a. Gruyere) cheese
To make the onions caramelize relatively quickly and evenly, use a mandolin to slice the onions very thin. The idea is to evaporate as much water as possible, and caramelize the sugars in the onions without burning them.
Add the butter to a large dutch over and melt. Add the onions, salt and sugar and cook over medium high heat, stirring occasionally until the onions are wilted and just starting to turn brown (about 20-30 minutes). Turn down the heat and continue caramelizing, stirring frequently to prevent burning (about 30-40 minutes).
When the onions are sticky, glossy, and a medium brown, add the sherry. Deglaze the pan by scrapping up all the browned bits from the bottom of the pot and reduce again, until the onions are sticky, glossy and dark brown (about 10 minutes). Add the beef stock, demi-glace, marjoram, bay leaf, then salt and pepper to taste. When salting, keep in mind the soup will reduce a bit when you’re melting the cheese on top, so don’t make it too salty. Let this simmer for about 10-15 minutes for all the flavors to meld.
Ladle the onion soup into broiler-safe ramekins, crocks, or mini cocottes (there should be enough soup for 4-6 individual servings depending on the size of your bowls). Don’t fill the containers all the way. Top with the soup with 2-3 slices of toasted bread and push them into the soup. Top the soup with a generous helping of cheese.
Place your ramekins on a baking sheet. Move the oven rack to the top position, and turn on the boiler. Put the baking sheet in the oven with the French Onion Soup directly below the heating element. Keep an eye on them to prevent burning and broil until the cheese is hot, and bubbly, and lightly browned. Serve right away.