Despite what restaurants would have you think, onion soup is all about the incredible amount of flavor you can coax from onions and well-made stock—not about toast piled with gooey cheese. Though beef stock is often the base, I prefer a deep, rich vegetable stock with a few dried mushrooms added to the pot.
Makes: 4 servings
Time: About 1 hour
4 large onions, peeled
4 tablespoons (1/2 stick) butter
5 cups vegetable stock or water
2 or 3 sprigs fresh thyme or a pinch dried
2 or 3 sprigs fresh parsley
1 bay leaf
2 tablespoons cognac or other brandy (optional)
Salt and pepper
4 My Kind of Croutons, made with bread slices and butter (optional)
1 cup grated Parmesan, Gruyère, or Emmental cheese (optional)
1. Halve the onions top to bottom and slice them as thinly as you can manage. Put the butter in a large pot over medium heat. When the butter melts, add the onions and cook, stirring occasionally, until very soft and beginning to brown, 30 to 45 minutes. Adjust the heat so they slowly turn into a melting mass and don’t brown too fast. Don’t rush.
2. Heat the oven to 400°F if you’re using the croutons and cheese. Add the stock, raise the heat to medium-high, and bring to a boil. Adjust the heat so the mixture bubbles gently. Add the thyme, parsley, and bay leaf and the cognac if you’re using it, sprinkle with salt and pepper, and cook, stirring occasionally, until the soup thickens a bit, about 15 minutes. Remove the bay leaf and herb sprigs. (At this point, you can refrigerate the soup, covered, for up to 2 days; reheat before proceeding.)
3. If you’re using the croutons and cheese, put 4 ovenproof bowls in a roasting pan or on a sturdy cookie sheet. Put a crouton in each bowl, ladle over the soup, and top with cheese. Bake for 5 to 10 minutes, just long enough to melt the cheese. Serve immediately.