The first topping you need is sliced cheese. I recommend American cheese or cheddar cheese. But there are other options! (The more Monterey Jack cheese, the better!) I would also recommend thinly sliced tomatoes. Roma tomatoes are my favorite for burgers, sliders, and sandwiches. Also, add a thick layer of lettuce. If you enjoy hots, you should add diced onions and spicy peppers. For condiments, sliders are best with ketchup, mustard, and relish. If you add sliced pickles – then you don’t need relish! (I prefer sliced pickles anyhow.) Thousand island sauce is also heavenly on cheeseburger sliders.