Remove loose outer leaves from the cabbage head and discard.
Quarter the cabbage and discard the hard central core.
Slice the cabbage into very thin ribbons using a knife or mandoline.
Grate the peeled carrots using the large holes of a box grater.
In a small bowl, whisk together apple cider vinegar, olive oil, Dijon mustard, and honey until smooth.
Season the dressing with salt, black pepper, and celery seed.
Place the shredded cabbage and carrots into a large mixing bowl.
Pour the dressing over the vegetables and toss thoroughly to ensure even coating.
Let sit for 10 minutes before serving to allow flavors to meld.