Prepare the Dressing:
In a medium bowl, whisk together the mayo, apple cider vinegar, Dijon mustard, maple syrup, celery seeds, sea salt, and several grinds of fresh black pepper. Set aside.

Prep the Vegetables:
Shred the green and red cabbage using a sharp knife, food processor, or mandoline. Use a vegetable peeler to create thin ribbons of carrots. Chop the scallions finely.

Combine the Vegetables:
In a large bowl, toss together the shredded green cabbage, red cabbage, carrot peels, and scallions until well-mixed.

Dress the Coleslaw:
Pour the dressing over the vegetable mix. Using tongs or clean hands, toss everything until evenly coated.

Adjust the Seasoning:
Taste and add more salt, pepper, or even a splash of vinegar if needed.

Chill and Serve:
Refrigerate the coleslaw for 20-30 minutes to allow the flavors to meld. Serve cold.