Make a Better French Onion Soup

BY RHODA BOONE

Onions. Broth. Bread. Cheese. Treat these elements right, and you’ve got a roadmap to the ultimate winter soup.

PHOTO BY CHARLES MASTERS, FOOD STYLING BY SUE LI

Leave it to the French to make a glorious, silky soup from a vegetable as ordinary as an onion. But if it’s so easy to make, why are we often subjected to shoddy bowls of thin, tasteless onion-water? Or, worse, acrid burnt onion broth? Or even worse: a cloudy, oily mess? Like many straightforward dishes, the outcome relies on nailing the technique and deploying just the right ingredients. So the Epicurious Test Kitchen merged the best parts of the recipes on our site to create Our Favorite French Onion Soup. (Scroll down to get straight to the recipe!)

Here’s how we cracked the code on this time-honored recipe:

PAIR BEEF BROTH WITH WHITE WINE (AND SKIP THE FLOUR)

Let’s start with the foundation for our soup. We’ve seen recipes that use beef broth, chicken broth, or a mix of the two. We’ve also seen recipes that call for red wine, white wine, or no wine at all. Our taste tests revealed the combination of an all-beef broth with white wine as the clear winner, as used in this Gourmet French Onion Soup. The beef broth (obviously home-made is best, but store-bought works too) adds an underlying richness to the soup, and we favored the lightness and acidity that white wine brings to the table.We also tested thickening the soup with flour as well as omitting it from the recipe. We preferred the no-flour version, as used in this Bon Appétit rendition, which provides a beautiful clear broth without muddying the sweet and savory flavors of the soup.

PHOTO & FOOD STYLING BY RHODA BOONE

CARAMELIZE YOUR VIDALIA ONIONS SLOWLY

As we read through your comments on the French Onion Soup recipes on the site, we heard you loud and clear: “More onions!” After all, it’s not called “Broth Soup” or “Cheesy Bread Soup.” So we took a cue from another Bon Appétit recipe and upped our onion-to-broth ratio to let the main ingredient shine.

We also found many recipes that just called for “onions.” But what kind of onions make for the best soup? We tried caramelizing red, yellow, and Vidalia onions and—shocker—the sweet Vidalias came out on top. Just a sprinkle of sugar and salt (and heat) transform these sweet onions into sweet, nutty, silky strands of pure gold.

But perfectly caramelized onions take time. Undercook your onions, and you’ll miss out on all that the savory sweetness. Some recipes call for cooking them for as little as 15 minutes, but we felt that this was not enough time to draw out their full flavor potential. Cook them too quickly over heat that’s too high, and you risk burning them and adding a scorched, bitter taste to your soup, so resist the urge to speed up this step. This French Onion Soup with Comté calls for cooking the onions for about an hour, which we thought was just right. When your onions are an even, deep golden brown like the kind of tan everyone wanted in the 80s, you know they’re ready.

DON’T CLOBBER YOUR SOUP WITH HERBS

We initially tried adding a bundle of rosemary, thyme, and bay leaves to our soup, but found the rosemary to be a bit overpowering. The combination of thyme and bay leaves found in this recipe for Onion Soup with Loads of Thyme and Giant Gruyère Crostini was really well balanced, lending a subtle herbaceous flavor and aroma.

PHOTO & FOOD STYLING BY RHODA BOONE

GO FOR GRUYÈRE

We’re not naming any names, but we know some people who eat French Onion Soup mostly for the blistered, melty, cheesy cap on top. So of course we had to give this element as much attention as the rest of the soup. And, just like the onions, many recipes call for generic “Swiss cheese.” Again, we asked, “What kind of Swiss cheese?” We narrowed it down to two contenders: Emmentaler and Gruyère. We tried them separately and mixed together. The slightly sweet, salty, nuttiness of Gruyère as found in our ”Onion Soup with Loads of Thyme and Giant Gruyère Crostini" recipe won us over and was chosen to adorn our soup.

PHOTO BY CHARLES MASTERS, FOOD STYLING BY SUE LI

FINISH WITH A SPLASH OF SHERRY

Many recipes include brandy in the cooking process or to finish the soup. We tried adding a touch to our brew, but it was a little too sweet. So we took a tip from Mixed Onion Soup in Sourdough Bread Bowls and tried finishing our bowls with a splash of dry sherry. The sherry complements the nuttiness of the Gruyère beautifully and adds a bright finish to the soup, yet the raw alcohol flavor gets mellowed by the warm broth. All in all, it’s the perfect finishing touch.

RECIPE: OUR FAVORITE FRENCH ONION SOUP

INGREDIENTS

• 5 tablespoons unsalted butter, divided

• 3 pounds Vidalia onions (about 4 medium), halved lengthwise, peeled, and thinly sliced

• 1 tablespoon vegetable oil

• 1 teaspoon kosher salt

• 1/2 teaspoon freshly ground black pepper

• 1/2 teaspoon granulated sugar

• 1 1/2 cups dry white wine

• 6 cups homemade beef broth or store-bought low-sodium beef broth

• 10 sprigs thyme

• 2 bay leaves

• 1 baguette

• 1 garlic clove, cut in half lengthwise

• 2 teaspoons sherry, preferably Fino or Manzanilla

• 4 ounces Gruyère cheese, grated (about 1 cup)

• Special equipment: kitchen twine, six 8-ounce or four 16-ounce oven-safe ramekins or bowls (optional)

PREPARATION

In a large Dutch oven or other large pot, melt 3 tablespoons butter over medium heat. Add the oil and onions; cook onions are until softened, stirring occasionally, about 15 minutes. Add the salt, pepper, and sugar; continue to cook, stirring occasionally, until onions are deep golden brown and caramelized, reducing heat slightly if onions seem to be browning too quickly, 35 to 45 minutes more.

Add wine and raise heat to high. Cook until almost all liquid has evaporated, 8 to 10 minutes.

Tie thyme and bay leaves into a bundle with twine. Add broth and herb bundle to pot with onions. Bring to a boil, reduce to a simmer, and cook, uncovered, until broth is thickened and flavorful, 20 to 30 minutes. Remove from heat and whisk in remaining 2 tablespoons butter. Taste and adjust seasoning.

Heat the broiler. Cut two 1/2-inch baguette slices for every serving of soup. Place baguette slices on a rimmed baking sheet and toast in oven until crisp and dry but not browned, about 1 minute per side. Rub one side of each toast with the garlic clove and set aside.

Place ramekins or ovensafe bowls on a rimmed baking sheet, add 1/2 teaspoon of sherry to the bottom of each, and ladle soup on top. Top each serving of soup with two garlic-rubbed toasts. Divide cheese among the servings, covering the bread and some of the soup. Carefully transfer baking sheet to oven and broil until cheese is melted and bubbling, 4 to 8 minutes. (Alternatively, if using regular soup bowls: Top each garlic-rubbed toast with some cheese and return to broiler to melt, about 2 minutes more. Divide sherry and soup among bowls, sprinkle with remaining cheese, and top each serving with two cheese toasts.)