Cabbage and Apple Slaw
"    2  cups  shredded green cabbage
"    2  cups  shredded red cabbage
"    1/2  cup  mayonnaise
"    1/4  cup  sour cream
"    2  tablespoons  cider vinegar
"    1/2  teaspoon  celery seed
"    1/2  teaspoon  kosher salt
"    1/8  teaspoon  black pepper
"    1 large unpeeled Fuji apple-cored, quartered, and thinly sliced
"    2  tablespoons  finely chopped fresh flat-leaf parsley (optional)
In a large bowl, combine the green and red cabbages; set aside. In a medium bowl, whisk together the mayonnaise, sour cream, vinegar, celery seed, salt, and pepper. Add the apple slices. Pour over the cabbage and