Ingredients

  • 2 pounds freshly ground beef (preferably 80/20)
  • 1/2 cup champagne vinegar
  • 3 tablespoons mustard seed
  • 1 tablespoon honey
  • 1 teaspoon salt
  • 1 tablespoon vegetable oil
  • 3 medium onions, julienned
  • 1/4 cup veal stock or store-bought low-sodium beef or chicken stock
  • 8 very thin slices pancetta
  • Salt and freshly ground pepper
  • 4 brioche rolls
  • 4 ounces Taleggio cheese, sliced
  • 1 beefsteak tomato, sliced
  • 1 head Bibb lettuce, leaves separated

Method

  • Preheat the oven to 350 degrees F. Preheat the grill to high heat.
  • Start by forming the meat into 4 patties about 3/4-inch thick.
  • Refrigerate until ready to grill.
  • For the relish: Combine 2 cups water, the vinegar, seeds, honey and salt in a medium saucepan.
  • Bring to a simmer and cook over medium-high heat until the liquid has reduced to a creamy consistency, about 12 minutes.
  • Heat the oil in a medium skillet over medium heat.
  • Add the onions and cook, stirring occasionally until caramelized and golden brown, about 20 minutes.
  • Add the veal stock and cook until the skillet is dry, about 3 minutes.
  • Stir the onions into the mustard seed mixture and reserve until needed.
  • Meanwhile, lay the pancetta on a baking sheet and bake until golden brown and crispy, 12 to 15 minutes.
  • Sprinkle the burgers liberally with salt and pepper and grill until medium rare, 4 minutes per side.
  • Toast the buns on the grill and place 1 ounce of the cheese on top of each burger.
  • Close the lid until the cheese melts and becomes gooey, about 30 seconds.
  • Place the burgers on the buns and top each with the relish and 2 slices of pancetta.
  • Garnish with the tomatoes and lettuce and serve.