A delicious mashup of French Onion Soup and a great steakhouse burger, this recipe is a treat for anyone who likes a burger that feels a little over the top. A generous portion of caramelized onions cooks on the stove while a tender juicy meat patty cooks in the air fryer. The burger sauce features Worcestershire sauce, mayo, soy sauce, and Dijon mustard, which ties together the flavors coming through from onions.

 

Frequently Asked Questions

  • How long does it take to cook burgers in an air fryer ?

    Airfryers vary in heat distribution and how hot they get inside, so it’s important to use an instant-read thermometer to make sure you’re achieving the level of doneness you want. For a medium-rare burger, you’re looking for 130°F, (or 140°F for medium) when tested in the thickest part of the patty.

  • What is a good substitute for dry sherry?

    Dry sherry is traditional to French onion soup but you can substitute Shaoxing wine, marsala, dry vermouth, or madeira wine as these are all fortified wines good for cooking as well. For a non-alcoholic substitute, use beef broth or apple cider.

 

Notes from the Food & Wine Test Kitchen

Making an indentation in the center of the burger patties prevents them from bulging when cooked.

 

Make ahead

Refrigerate caramelized onions for up to three days and gently warm them on the stove or in the microwave before using. You can also prepare the burger patties and refrigerate them for up to one day prior to cooking.

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Ingredients

  • 2 tablespoons unsalted butter
  • 1 tablespoon extra-virgin olive oil
  • 1 1/2 pounds yellow onions, thinly sliced (about 5 cups)
  • 1 teaspoon fresh thyme leaves
  • 2 teaspoons kosher salt, divided
  • 1 1/2 teaspoons black pepper, divided
  • 1/4 cup, plus 1 teaspoon dry sherry, divided
  • 1 1/2 pounds 85/15 lean ground beef
  • 4 (1-ounce) Gruyère cheese slices
  • 1/2 cup mayonnaise
  • 1 tablespoon Worcestershire sauce
  • 1 teaspoon Dijon mustard
  • 1 teaspoon soy sauce
  • 4 sesame brioche hamburger buns, split and toasted

Directions

  1. Heat butter and oil in a large skillet over medium until melted. Stir in onions, thyme, 1 teaspoon salt, and 1/2 teaspoon pepper. Cook, stirring occasionally, until onions are translucent, about 3 minutes. Reduce heat to medium-low; cover and cook, stirring occasionally, until onions begin to soften and brown around edges, about 18 minutes. Uncover and increase heat to medium-high; stir in 1/4 cup sherry, scraping up any browned bits from bottom of skillet. Cook, stirring often, until sherry is evaporated and onions are browned and caramelized, 3 to 4 minutes.

  2. Divide meat into 4 (6-ounce) portions. Working with 1 portion a time, gently shape into a ball. Flatten ball between the palms of your hands, and shape into a 4 1/2-inch-wide patty (about 3/4-inch thick). Press your thumbs into center of patty, and create an indention (about 1/2-inch deep).

  3. Preheat a 6-quart air fryer to 400°F for 5 minutes. Sprinkle patties evenly with remaining 1 teaspoon salt and 1 teaspoon pepper. Working in batches, place 2 patties in a single layer in preheated air fryer basket; cook until patties form a browned crust on edges and a meat thermometer inserted into center of patties registers 130°F for medium-rare, 5 minutes, or until desired degree of doneness. Remove cooked patties; set aside. Repeat cooking process with remaining 2 patties. When remaining patties are cooked, transfer all patties back to air fryer. Place 1 cheese slice on each patty, and close air fryer; let stand just until cheese is melted, about 30 seconds. Remove patties; let rest for 2 to 3 minutes.

  4. While patties are cooking, whisk together mayonnaise, Worcestershire sauce, mustard, soy sauce, and remaining 1 teaspoon sherry in a small bowl. Set aside.

  5. Spread 1 tablespoon mayonnaise mixture on each of the top and bottom bun halves. Place 1 meat patty on each of the bottom bun halves. Divide caramelized onions into 4 portions (about 1/4 cup each), and place 1 portion on top of each meat patty; add top bun halves. Serve immediately.