Steakhouse French Onion Soup Au Gratin
Chapter 1: Starters & Salads
A ceramic crock of dark onion soup hits the table straight from a 500-degree broiler, armored in a blistered crust of melted cheese. Long before the dry-aged porterhouse arrives with its tableside spoon-baste, the wood-paneled dining rooms of Brooklyn demand forty-five minutes of constant stirring to collapse the raw alliums, so don't rush the caramelization, do not skimp on the butter, and let that cheese spill over the rim and burn a little. Hand out the heavy soup spoons, punch through the molten Gruyère blisters, and warn everybody not to touch the bowl.
Before you start
Preheat the broiler.
Position an oven rack exactly 6 inches from the broiler element and preheat to high (around 500°F) while the soup simmers.
Toast the sourdough.
Brush the sourdough slices with melted butter, toast them in a cast-iron skillet until crisp, and aggressively rub the edges with the cut side of a raw garlic clove.
Ingredients
- yellow onions4 large
- sweet onion1 large
- unsalted butter6 tbsp
- olive oil1 tbsp
- kosher salt1 tsp
- freshly ground black pepper1/2 tsp
- garlic3 med
- fresh thyme leaves1 tbsp
- dried bay leaves2 med
- dry Sherry1/2 cup
- all-purpose flour2 tbsp
- beef bone broth4 cup
- chicken bone broth4 cup
- unflavored gelatin1/4 oz
- Worcestershire sauce1 tbsp
- Cognac2 tbsp
- rustic sourdough4 large
- raw garlic1 med
- aged Gruyère cheese8 oz
- aged Provolone cheese4 oz
- Parmigiano-Reggiano2 oz
Method
- 01
Collapse the alliums.
In a large, heavy-bottomed cast-iron Dutch oven, heat the olive oil and melt the butter over medium heat. Toss in all the sliced onions and kosher salt, tossing thoroughly to coat them in fat, then cover tightly with a lid for 10 minutes to trap the steam and force the release of their cellular water.
- 02
Commit to the caramelization.
Remove the lid, drop the heat to medium-low, and cook uncovered for 45 to 60 minutes. Stir every 5 minutes, scraping the bottom of the pot with a wooden spoon to lift the sticky, browned sugars, until the onions surrender into a jammy, deeply mahogany-colored paste.
- 03
Bloom the aromatics and toast the flour.
Push the caramelized onions to the perimeter of the pot, dropping the minced garlic, fresh thyme, and bay leaves into the center to sauté for 60 seconds until highly aromatic. Sprinkle the all-purpose flour evenly over the mixture and cook, stirring constantly, for 3 minutes to eliminate the raw starch.
- 04
Deglaze aggressively.
Crank the heat to medium-high and pour in the dry Sherry. As it hisses and boils aggressively, use the liquid to scrape up every remaining bit of dark fond from the bottom of the Dutch oven, cooking until the sherry has almost completely evaporated.
- 05
Build the decadent broth.
Pour in the beef broth, chicken broth, the bloomed gelatin, and the Worcestershire sauce. Bring the soup to a rolling boil, then immediately drop the heat to a gentle simmer.
- 06
Simmer and fortify.
Let it simmer uncovered for 30 to 45 minutes to meld the flavors and thicken slightly, then remove from heat, discard the bay leaves, and stir in a finishing splash of Cognac. Taste and adjust the seasoning with heavy black pepper.
- 07
Construct the armored crocks.
Ladle the hot soup into four heavy, oven-safe crocks, leaving an inch of space at the top. Float a piece of the garlic-rubbed toast in each crock.
- 08
Broil the canopy.
Toss the Gruyère, Provolone, and Parmigiano-Reggiano together and mound the blend heavily over the toast, ensuring it spills over the edges of the crocks. Slide them under the broiler for 3 to 5 minutes, watching like a hawk, until the cheese bubbles violently and develops deep, blistered brown spots.
Notes
The Gelatin Trick.
Elite steakhouses rely on veal bones or oxtail to give their broth a lip-coating, gelatinous viscosity. Blooming a packet of unflavored gelatin into a high-quality store-bought broth achieves that luxurious mouthfeel without requiring a 48-hour veal reduction.
The Sherry Mandate.
Do not dare reach for "cooking sherry" from the supermarket aisle. Use a drinkable, dry Fino or Amontillado sherry; if you wouldn't pour it in a glass, it has no business deglazing your onions.