I’ve made sliders about 4 or 5 times in the past couple months and they’ve gotten really good. I use Gibsons seasoning salt, a higher protein beef (88/12 was the last one), white onions, and Hawaiian rolls. Add whatever cheese we have at the time.
I brought one to my neighbor and he suggested horseradish sauce, which was absolutely stellar.
My kids, my wife, and my neighbors all say they’re amazing.
I use butter to get some of that fatty/salty flavor into there and it’s easier to maintain size and shape when the fat from the beef isn’t rendering out into the pan