2 tablespoons extra-virgin olive oil (EVOO)
1 small onion, finely chopped
2 large cloves garlic, finely chopped
1 cup parsley, loosely packed, finely chopped
1 teaspoon red pepper flakes (1/3 palm full)
1½ pounds ground sirloin (85%)
Salt and pepper
½ cup aquafaba spread or mayonnaise
¼ cup ketchup
2 tablespoons balsamic drizzle or aged balsamic vinegar
4 slices deli-sliced provolone cheese, sliced on the thicker side
4 artisan style or ciabatta rolls, warmed or charred and split
Baby kale or arugula
4 slices speck, smoked prosciutto or other smoky ham
Heat a skillet over medium to medium-high heat, add olive oil, 2 turns of the pan, then add onions and garlic and cook 5 minutes. Remove to bowl and cool.
Combine the cooled onions and garlic with parsley, zest and juice of a lemon, and chili flakes. Combine the onion-gremolata mixture, beef, and salt and pepper. Form 4 patties, thinner at the center and thicker at the edges.
Heat a cast-iron skillet over medium-high heat.
Combine mayo, ketchup and balsamic vinegar.
Cook patties 8 minutes, turning occasionally, and melt cheese over burgers.
Build burgers: bun bottom, balsamic sauce, baby kale or arugula, cheeseburgers, folded ham, balsamic sauce on bun top.