Start with a high-quality 80% lean ground beef. Form into 8 uniformed patties. Make a thumbprint in the middle of the patty. This ensures the burger doesn't puff up in the middle and make an odd shape.
Generously sprinkle both sides with salt and pepper. Make sure to add enough salt as it brings out the natural flavors in the beef.
Preheat grill to medium-high. Cook sliders for about 4-5 minutes per side, depending on your desired level of doneness.
With about 1 minute left of cooking time, add cheese and let it melt onto the burger patty.
Place on condiment covered buns. Top with desired toppings.
In-N-Out Spread Recipe:
In a small bowl, combine all ingredients and stir together. Cover and refrigerate until chilled. The flavor will develop and become stronger in time.