Mince and mash 1 garlic clove with 1/4 teaspoon kosher salt into a chunky paste. Whisk the garlic paste, 1/2 cup sour cream, 1/3 cup buttermilk, 1/4 cup mayonnaise, 2 teaspoons vinegar and 2 tablespoons chopped chives in a bowl. Season with salt and pepper.