Beef Sliders with Provolone and Balsamic Onions

Preparation

1. Step 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.

   Step 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.

   Step 3

   While patties are resting, grill the buns, cut side down, until lightly charred around the edges, about 30 seconds.

   Step 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.

   Step 5

   Build sliders with patties, buns, onions, and aioli.

2. Do Ahead

   Step 6

   Patties can be formed 6 hours ahead. Cover and chill.