Spoon buttermilk, vinegar, chopped chives, mayonnaise, salt and pepper in a small mixing bowl.
Mix with a mixing spoon or wire whisk until very well blended. Place in a jar and cover and place in fridge for at least an hour before serving.
Remove from refrigerator and whisk with a small whisk before serving over a fresh salad. You can cover and refrigerate this creamy chive salad dressing up to 3 days.