In a large bowl, whisk ½ cup of mayonnaise, ½ cup of sour cream, 1½ tablespoons of apple cider vinegar, 2 teaspoons of Dijon mustard, 2 tablespoons of sugar, ¾ teaspoon of celery salt, and ¼ teaspoon of black pepper.
Add 7 cups of finely shredded green cabbage and 1 medium shredded carrot, and toss well to coat.
Set aside for at least 20 minutes, preferably 2 hours, until the cabbage wilts. Toss again before serving.
