1½ pounds ground beef
2 teaspoons Worcestershire sauce
1 teaspoon kosher salt
½ teaspoon ground black pepper
12 slices sourdough bread
½ cup Secret Sauce
3 medium Vidalia onions, thinly sliced
6 slices Cheddar cheese
8 tablespoons unsalted butter
14 cup mayonnaise 14 cup Dijon mustard
1 tablespoon sauce (bbq)
12 tbsp. hot sauce
Combine mustard, mayonnaise, barbecue sauce, and hot sauce in a small bowl. Refrigerate for up to 3 days, covered.
Combine the ground beef, Worcestershire sauce, salt, and pepper in a large mixing basin. Make 6 oval patties out of ground beef.
2 tablespoons butter, melted in a medium cast-iron skillet over medium heat Toss in the onion. Cook, stirring periodically, for 35 minutes, or until onion is tender and golden brown.
Cook patties in a large cast-iron skillet over medium-high heat for 2 minutes per side, or until browned and cooked through. Turn off the heat in the skillet. Remove the patties from the skillet and wipe it clean.
1 slice of bread, 1 tablespoon Secret Sauce, 2 to 3 tablespoons caramelized onions, 1 slice cheese, 1 patty, 1 tablespoon Secret Sauce Add another slice of bread on top. Replace the remaining bread, Secret Sauce, caramelized onions, cheese, and patties with the remaining ingredients.