system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do they serve pickles when you order a sandwich?

I think this is an American thing but I was just wondering why.
gpt
Because they're awesome!

But speaking from a culinary standpoint, the vinegar and acidity from the pickle refreshes your palate between bites and brings some balance to the sandwich. Typically, American sandwiches are focused on combinations of meats and cheeses. All that fat can be balanced out with a bite of something acidic.

Sidenote: this is also why they almost always serve pickled ginger or daikon radish with sushi. Usually when you order sushi, you get a few different types with varying ingredients. You're supposed to eat some of the pickled garnish before trying each type so that your palate gets refreshed. That way you can fully taste the differences and delicate flavors of each different type of sushi as you progress through the meal.