In a mixing bowl, whisk together ½ cup mayonnaise, 1 clove minced garlic, 1 teaspoon fresh lemon juice, and ¼ teaspoon salt until smooth and creamy. Set aside in the refrigerator.

In a shallow dish, combine 24 ounces of skirt steak with 2 tablespoons of brown sugar, 2 tablespoons of balsamic vinegar, 1 tablespoon of vegetable oil, ½ teaspoon kosher salt, and ⅛ teaspoon coarse ground black pepper. Marinate for at least 15 minutes.

Melt 3 tablespoons of unsalted butter in a hot skillet over medium heat. Add 2 large sliced yellow onions and cook for 10-12 minutes until golden brown and caramelized.

Increase the skillet heat to high and place the marinated skirt steak in the skillet. Sear for 3-4 minutes on each side, or until reaching your desired doneness. Let the steak rest for a few minutes.

Spread a little butter on the cut sides of 4 hoagie rolls and toast them in the same skillet until golden brown.

Assemble the sandwich by spreading garlic aioli on the toasted rolls, layering with provolone cheese, arugula, sliced skirt steak, and caramelized onions. Close the rolls and serve warm.