Pickled toppings add acidity and crunch that cut through rich meat and cheese. Classic dill pickles or bread-and-butter slices work well as-is, but quick-pickled onions, jalapeƱos, or cucumbers are simple to make and customize.
To quick-pickle: slice the vegetable thinly and pour over a hot brine of equal parts vinegar and water, salt, and a bit of sugar. Let sit at room temperature for 30 minutes to an hour, or refrigerate overnight for deeper flavor.
Pickles introduce acidity, which brightens the overall bite and prevents the burger from tasting heavy or one-note.