Chop the small onion finely and set aside. Preheat your skillet over medium-high heat until it shimmers, and toast the cut sides of the mini buns for about 3-4 minutes until golden and crispy. Remove and set aside.
Divide the ground beef into four equal portions, gently shape each into a ball, then flatten into about 1.5 cm thick patties. Season generously with salt and pepper on both sides.
Place the skillet back over medium-high heat. Carefully place the patties into the hot pan, listening for a sizzle. Cook for 2-3 minutes until the edges are crispy and browned.
Flip the patties using a spatula and cook for another 2-3 minutes until the other side is browned and the interior is cooked to your desired doneness. During the last minute, place a slice of cheese on each patty to melt.
While the patties finish cooking, add the finely chopped onions to the skillet and cook, stirring occasionally, for about 8-10 minutes until golden and caramelized. The onions should smell sweet and look deep golden.
Remove the beef patties from the skillet and let them rest for a minute. Place the toasted buns on a serving plate. Assemble each slider by placing a patty with melted cheese on the bottom bun, topping with caramelized onions, a pickle slice, and your choice of condiments. Cover with the top bun.
Serve the mini sliders immediately while hot, with extra condiments on the side for dipping or topping. Enjoy the crispy, juicy bites that balance flavor and texture perfectly!
