French Onion Soup


under 120mins
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Ingredients for servings

  • 90 g unsalted butter, plus more for toasts

  • 3 pounds yellow or mixed onions, french cut see note

  • kosher salt and freshly ground black pepper

  • 120 ml dry sherry such as Amontillado

  • 2 pounds homemade or store-bought low-sodium chicken stock

  • 2 sprigs thyme

  • 1 bay leaf

  • 5 ml Asian fish sauce optional

  • 5 ml cider vinegar

  • 8 bowl-size slices rustic bread, toasted until crisp

  • 1 medium clove garlic

  • 450 g Gruyère cheese, grated

  • freshly minced chives, for garnish

Directions

  • In a large stainless steel saucepan, or in 2 large stainless steel or cast iron skillets, melt butter over medium-high heat until foaming. Add onions and cook, stirring occasionally, until softened, about 8 minutes. Lower heat to medium-low and cook, stirring frequently, until onions are very sweet and a rich golden-brown color, 1 to 2 hours. If browned onion juices on bottom of pot threaten to burn, add 1 tablespoon (15ml) water, scrape up browned bits, and continue cooking. Season with salt and pepper.

  • Add sherry and bring to a simmer, scraping up any browned bits. (If using 2 skillets, divide sherry between them, then scrape onions and liquid from both pans into a pot or Dutch oven to continue.) Cook until alcohol smell is mostly gone, about 3 minutes. Add stock, thyme, and bay leaf; raise heat to medium-high; and bring to a simmer. Lower heat and simmer for 20 minutes.

  • Add fish sauce, if using, and cider vinegar. Season with salt and pepper. Discard thyme sprigs and bay leaf.

  • Preheat broiler and adjust oven rack to top position. Butter toasts and rub with garlic clove until fragrant. Spoon a small amount of broth into the bottoms of 4 ovenproof serving bowls, then top with half the toasts. Sprinkle some grated cheese on top of toasts, then spoon more soup and onions on top, nearly filling bowls. Set remaining 4 toasts in bowls, pushing to nearly submerge them. Top with remaining grated cheese and set bowls on a rimmed baking sheet. Broil until cheese is melted and browned in spots. Garnish with chives and serve.

Notes

Caramelizing the onions slowly in butter until they’re rich golden-brown (but not so dark as to taste bitter) produces the sweetest, most flavorful results.

The homemade or store-bought chicken stock used here is typically better-quality than the store-bought beef stock many recipes call for.

Asian fish sauce, cider vinegar, and sherry add depth and complexity to the broth.

Yellow onions are your best all-purpose bet for this soup, but a mix of yellow, sweet (e.g., Vidalia), and red onions, as well as shallots, produces an even more complex flavor.

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