- 4 slices red onion, about 1/4 in. thick
- 2 tablespoons balsamic vinegar
- 1/4 cup olive oil, divided
- 3/4 cup chopped giardiniera*
- 1/3 cup mayonnaise
- 1 tablespoon chopped fresh oregano leaves
- 1 1/2 pounds ground lean beef
- 1 teaspoon kosher salt
- 1/2 teaspoon pepper
- 4 ciabatta or focaccia buns, split
- 4 slices provolone cheese
- About 2 cups lightly packed arugula
- calories 718
- caloriesfromfat 62 %
- protein 42 g
- fat 50 g
- satfat 14 g
- carbohydrate 19 g
- fiber 1.4 g
- sodium 1449 mg
- cholesterol 130 mg
How to Make It
Heat grill to medium (350° to 450°). Put onion in a small bowl and toss with vinegar and 1 tbsp. oil; set aside. Mix giardiniera with mayonnaise and oregano; set aside.
Season beef with salt and pepper, mixing with your hands until just combined. Divide into 4 portions and form into patties. Using your thumb, press a dent into the center of each patty (it will even out as the burger cooks). Brush patties lightly on both sides with 1 tbsp. oil. Brush cut sides of buns with remaining 2 tbsp. oil.
Drain onion and discard marinade. Grill onion and burgers until onion is softened and charred slightly, about 5 minutes, and until burgers are done the way you like, about 8 minutes for medium-rare. In the last 2 to 3 minutes of cooking, top burgers with cheese and lightly toast buns.
Assemble burgers, topping them with onion, arugula, and a hefty dollop of mayonnaise mixture.
*Find giardiniera in the pickle aisle of well-stocked grocery stores.