All ingredients ready? Let's begin!
In a large skillet over medium-high heat, add 1 tablespoon of the olive oil. As soon as it warms up, add the onions and peppers. Cook until the onions start to soften and caramelize, approximately 4 minutes. Stir occasionally. Remove the vegetables to a bowl and season with salt and pepper.
Add the remaining olive oil to the skillet. Add the steak and cook until just browned, stirring to cook all sides. Season with salt and pepper.
Preheat your oven to 350°F. Grab a 7 x 11-inch baking dish.
Remove the buns from the package in one piece (if possible). Using a serrated bread knife, slice the buns through the center horizontally. Place the bottom half of the rolls inside the baking dish.
Layer the steak across the bottoms of the buns. Then, layer the onions and peppers evenly on top of the steak. Add the cheese to the onions and peppers.
Place the tops of the buns on the slider filling and press down gently with your hands. Pour or brush the melted butter over the tops of the buns.
Cover the dish with aluminum foil. Place the dish in the oven and bake for 10 minutes.
Remove the foil from the dish and continue to bake until the tops of the buns start to brown and the cheese has melted, approximately 10 more minutes.
Transfer the hot sliders to a serving platter and enjoy immediately.