Make the Big Mac Sauce: In a medium mixing bowl, combine mayonnaise, French dressing, sweet pickle relish, minced onion, vinegar, sugar, onion powder, and paprika. Mix the ingredients thoroughly until they form a smooth and creamy consistency. Cover the bowl and place it in the refrigerator for at least 30 minutes to let the flavors blend and enhance the taste.
Prepare the Buns: Preheat your oven to 375°F (190°C). Using a serrated knife, carefully slice the potato slider buns in half horizontally, ensuring they remain intact. Arrange the bottom halves of the buns, cut-side up, on a baking sheet. Lightly brush both the tops and bottoms of the buns with melted butter to enhance flavor and texture. Toast the buns in the oven for 3–5 minutes until golden brown. If desired, sprinkle sesame seeds over the top halves before baking for an authentic Big Mac touch.
Cook the Beef: Heat a large skillet over medium heat and place the ground beef in the pan. Break the beef apart with a spatula and cook until it begins to brown. Evenly sprinkle the salt, black pepper, garlic powder, onion powder, and ground oregano over the beef. Stir occasionally and continue cooking until the beef is fully browned and cooked through. Drain any excess grease from the skillet to prevent sogginess. Reduce the heat to low, then mix in 8 slices of American cheese until melted and fully incorporated.
Assemble the Sliders: Lay a slice of American cheese on each of the toasted bottom buns. Evenly spread the cooked beef mixture over the cheese, ensuring every bun has a generous portion. Preheat the oven to 375°F (if it was turned off) and place the sliders back in the oven for 3–5 minutes to melt the cheese. Remove the sliders from the oven and layer them with shredded lettuce, dill pickle chips, and minced onions. Spread the prepared Big Mac sauce on the underside of the top buns before placing them over the assembled sliders.
Serve and Enjoy: Carefully slice the assembled sliders into individual portions. Arrange them on a serving platter and enjoy immediately while warm. Serve with your favorite sides like French fries, onion rings, or a crisp salad for a complete meal.