Preheat the oven to 350°F (175°C). Line a baking sheet or 9x13-inch baking dish with parchment paper or lightly grease it.

In a small bowl, mix the mayonnaise, red wine vinegar, Italian seasoning, garlic powder, salt, and black pepper until smooth.

Place the bottom halves of the slider buns in the prepared baking dish. Spread the seasoned mayonnaise evenly over the buns.

Layer the provolone, ham, turkey, and salami over the bottom buns, folding the meat as needed so it fits evenly.

Add the shredded lettuce, tomato slices, red onion, and pepperoncini on top of the meat.

Place the top halves of the buns over the sliders.

In another small bowl, stir together the melted butter, dried parsley, and Parmesan cheese. Brush the mixture over the tops of the buns.

Cover loosely with foil and bake for 10 minutes. Remove the foil and bake for 5 to 7 minutes more, until the cheese is melted and the tops are lightly golden.

Let the sliders rest for 2 to 3 minutes, then slice and serve warm.