Prepare Vegetables:
In a large bowl, combine shredded green cabbage, purple cabbage (if using), and carrots.
Make Dressing:
In a separate bowl, whisk together mayonnaise, apple cider vinegar, Dijon mustard, honey, salt, and pepper until smooth. If desired, add milk or buttermilk for a creamier consistency.
Combine:
Pour dressing over shredded vegetables. Toss well until evenly coated.
Chill:
Cover and refrigerate for at least 30 minutes to allow flavors to meld.
Serve:
Serve chilled as a side dish for BBQs, sandwiches, or as a topping for tacos and burgers.