Onion Soup Recipe
- 6 tablespoons (90 g) unsalted butter
- 4 large onions, thinly sliced
- 1 cup (250 ml) dry white wine or flat Champagne
- 1 cup (250 ml) Beef Stock or, in England, imported beef or meat stock
- 5½ cups (1.4 L) Basic Chicken Stock or commercial chicken broth
- 1 tablespoon kosher salt, or less if using commercial broth
- Freshly ground black pepper, to taste
- Twelve ¾-inch (1.9-cm) diagonal slices Italian or French bread, toasted
- 5 ounces (150 g) Gruyere cheese, coarsely grated (1½ cups)
- 1 cup (60 g) freshly grated Parmesan; or ½ pound (225 g) low-fat mozzarella cheese, sliced across into 32 slices
- In a large wide pot, melt the butter over medium heat. Add the onions—to keep them from stewing rather than browning, spread them in as close to a single layer as possible. Cook, stirring occasionally, until they are very brown and soft, about 30 minutes; they will need more frequent stirring toward the end.
- Stir in the wine and bring to a boil, scraping the bottom of the pan vigorously with a wooden spoon to get up all of the browned bits.
- Continue scraping while pouring in the beef stock. Then pour in the chicken stock. Season with the salt and pepper. Bring to a boil. Lower the heat and simmer for 10 minutes. The soup can be made ahead to this point and refrigerated for up to 3 days.
- To gratiné, preheat the broiler and, if necessary, return the soup to the simmer.
- Lay 2 slices of toast in the bottom of each ovenproof bowl or crock, or make two layers of bread in a large earthenware casserole.
- If using, mix together the Gruyere and Parmesan. Pour the soup over the slices of bread. Sprinkle the cheese mixture evenly over the soup.
- Or, if using the mozzarella, lay 4 thin slices over the top of each serving or all the slices over the entire contents of the casserole.
- Place the containers under the broiler for 3 to 4 minutes until bubbling and brown.