Buttermilk
Buttermilk is in 15 recipes and does two things to chicken at once. Its acidity is mild enough to tenderise the surface without turning the meat chalky the way lemon juice or vinegar does, and its thickness means the dredge grips instead of sliding off. Marinating times here run from a few hours to overnight — longer is not better past a point, and past a day the texture starts going soft. A cup of milk with a spoon of lemon juice is a workable substitute.
Often goes with
Recipes with buttermilk

KFC Zinger Burger (Copycat)

McDonald's McSpicy (Copycat)

KFC Classic Chicken Sandwich (Copycat)

KFC Spicy Chicken Sandwich (Copycat)

KFC Gravy Burger (Copycat)

KFC Smoky Mountain BBQ Sandwich (Copycat)

KFC Dirty Louisiana Burger (Copycat)

McDonald's Deluxe McCrispy (Copycat)

Copycat Red Robin Whiskey River BBQ Burger with Onion Straws

KFC Cheetos Chicken Sandwich (Copycat)

KFC Double Down (Copycat)

KFC Tower Burger (Copycat)

KFC Paneer Zinger (Copycat)

KFC Chicken & Donuts Sandwich (Copycat)

KFC Mac 'N Cheese Zinger (Copycat)