Place apples, kohlrabi, celery root, and celery into lemon water (acidulated water). (The apples, kohlrabi, celery root and celery may be kept in acidulated water, in refrigerator for up to 1 day before serving.)
Whisk mayonnaise, honey, vinegar, salt, and pepper together until smooth. Drain apple mixture and shake off water.
Toss apples, kohlrabi, celery root, and celery with vinaigrette. Season with salt and pepper to taste.
Garnish with pomegranate arils, parsley leaves, and celery leaves.
The finished slaw may be stored, covered, in the refrigerator for up to 6 hours before serving.