1Preheat a skillet over medium-high heat and add the olive oil.
Add the diced onions to the skillet and sauté until they are translucent, about 3-4 minutes.
Add the ground beef to the skillet, breaking it apart with a spatula. Cook until the beef is browned and fully cooked, about 6-8 minutes.
Season the beef with salt and black pepper, stirring to combine.
Reduce the heat to low and sprinkle the shredded cheddar cheese over the beef. Cover the skillet and let the cheese melt, about 2-3 minutes.
While the cheese is melting, slice the slider buns in half and lightly toast them in a separate pan or toaster.
Once the cheese has melted, remove the skillet from heat.
Assemble the sliders by placing a portion of the beef and cheese mixture onto the bottom half of each slider bun.
Top the beef with pickles and a drizzle of ketchup and mustard.
Place the top half of the slider buns on each slider.
Serve the sliders warm and enjoy!