Ingredients

• 2 lb. ground beef (20% fat)
• Kosher salt, freshly ground pepper
• 4 slices provolone piccante cheese, torn in half
• 8 potato slider buns
• 1 large red onion, very thinly sliced into rounds
• 3 Tbsp. balsamic vinegar
• 1 tsp. sugar
• Aioli or store-bought mayonnaise (for serving)

Instructions

1. Divide meat into 8 portions (about 4 oz. each). Place 1 portion on a work surface. Cup your hands around the meat and shape it into a rounded mound. Gently flatten patty to about 3/4" thick. Season both sides with salt and pepper. Repeat with remaining portions of meat.
2. Prepare a grill for medium-high heat. Grill patties until lightly charred on bottom, about 3 minutes. Flip and top with a piece of cheese. Grill to desired doneness (cheese should be melted), about 3 minutes for medium-rare. Transfer patties to a cutting board and let rest 5 minutes.
3. While patties are resting, grill the buns, cut side down, until lightly charred around the edges, about 30 seconds.
4. Toss onion with vinegar, sugar, and a pinch of salt in a medium bowl and let sit, squeezing onions occasionally to soften slightly, 5 minutes.
5. Build sliders with patties, buns, onions, and aioli.
6. Patties can be formed 6 hours ahead. Cover and chill.