- 1 tablespoon extra-virgin olive oil
- 2 large onions, halved and thinly sliced
- Kosher salt
- 1/4 cup dry white wine
- 1 tablespoon soy sauce
- 6 cups beef stock or low-sodium broth
- Four 1/2-inch-thick slices of whole-grain baguette
- 1/4 cup freshly grated Gruyère cheese
- In a large enameled cast-iron casserole, heat the oil until shimmering. Add the onions and cook over moderate heat, stirring occasionally, until the onions are wilted and just starting to brown, about 7 minutes. Add a generous pinch of salt and cook over moderately low heat, stirring occasionally, until the onions are soft and golden, 25 to 30 minutes.
- Add the wine and soy sauce to the casserole and cook over moderate heat, scraping up any browned bits from the bottom, until evaporated, about 3 minutes. Add the stock and bring to a boil. Simmer over moderately low heat, stirring occasionally, until the broth is well flavored and slightly reduced, about 10 minutes. Season the soup with salt.
- Meanwhile, preheat the broiler. Arrange the bread on a baking sheet and top each piece with 1 tablespoon of the cheese. Broil 6 inches from the heat until the cheese is melted and just starting to brown, about 2 minutes. To serve, ladle the soup into bowls and top with the toast.
Make AheadThe recipe can be prepared through Step 2 and refrigerated for up to 2 days. Reheat gently.
NotesOne Serving: 145 cal, 6 gm fat, 1.6 gm sat fat, 14 gm carb, 2 gm fiber, 8 gm protein.