A classic French onion soup recipe requires only a few humble and inexpensive ingredients, doesn’t require a lot of hands-on time, and results in something far better than the sum of its parts. You can serve this with the popular accoutrements (a giant crouton, or smothered in cheese and gratineed), but to my palate, it doesn’t need anything additional to completely satisfy.
As with many recipes made from so little, the quality of the ingredients matters. There are two keys to getting a basic French onion soup right: first, use a full-bodied homemade beef stock. Not sure if yours qualifies? It should gel when cold and leave your lips just a bit sticky when you sip it warm. Traditional French onion soup is sometimes slightly thickened with flour, but if you use a good stock, the flour is totally unnecessary and even undesirable (and that also means you’ll have a gluten-free French onion soup, which shouldn’t be hard to find but apparently is). Second, make sure you give the onions plenty of time to caramelize. Go too fast, and the onions won’t develop their maximum flavor and your soup will fall flat. If you are unsure about how to do this, I’ve got you covered. As long as you do these two things, this will easily be your new favorite simple French onion soup recipe.
Basic French Onion Soup
2 softball-sized yellow onions, cut in half and sliced
2-3 Tablespoons butter
5 cups homemade beef stock
1/4 cup dry vermouth or dry white wine (I prefer vermouth here, but use what you have)
1. Place the onions, a few healthy pinches of salt, and butter in a large pot over low heat. Sweat the onions in the butter for about ten minutes, then turn the heat up to medium just until the onions start to take on a tiny bit of color. Maintain the heat so that the onions are very slowly losing volume and gradually coloring- you absolutely do not want to brown them, but instead have them slowly coloring, collapsing more and more, until you eventually have an almost jammy mass of caramelized onion. This should take about an hour, and as cooking continues, you’ll need to stir more often to avoid any sticking or browning.
2. When the onions are almost done, heat the broth on the stove. Once the onions have fully caramelized, add the vermouth and stir, scraping all the browned bits up from the bottom, and then pour the broth into the pot and bring to a simmer. Keep the soup at a bare simmer for 30-45 minutes. Serve immediately, or store in the refrigerator for several days and reheat before serving. You can also freeze this for several months, if you’d like.