Beef Sliders with Avocado and Pickled Onions

To make the pickled onions, place the sliced onions into a heatproof jar. Combine vinegar, water, sugar and 1 teaspoon salt in a small saucepan. Let simmer just until the sugar has dissolved and immediately pour over the onions. Let sit at room temperature until cooled.

Form the meat into 8 (4”) patties. Making sure to flatten them in the middle to create a small well, this will help them keep their shape as they cook. Season generously with salt and pepper and let sit at room temperature at least 5 minutes before cooking.

To cook the burgers, heat a medium cast-iron pan over medium-high heat. Drizzle about a teaspoon of vegetable oil into the pan. Working in batches of 4 sear the beef burgers for 2 minutes on one side then turn, top with a mound of cheddar, cover and continue to cook another 2 minutes, just until the cheese has melted. Remove from pan and continue with the remaining sliders, allowing burgers to rest after cooking.

Toast the buns, cut side down on a griddle or another skillet.

To assemble, place a patty on the bottom bun, top with pickled onions, tomatoes, lettuce and avocado. Spread some mayonnaise on the top bun and place on the burger. Serve with sweet potato fries, if using.