Start with a firm green cabbage. Peel off the limp outer leaves.

Cut it into quarters and remove the tough core.

Slice each quarter into thin ribbons with a sharp knife.

Grate the carrots on the large holes of a box grater.

Slice the onion paper thin, if using.

In a large bowl, combine shredded cabbage, grated carrot, and onion.

In a separate bowl, whisk together mayonnaise, apple cider vinegar, sugar, mustard, celery seed, salt, and pepper.

Add dressing to the vegetables gradually, starting with three-quarters of it. Toss to combine.

Taste and add more dressing if needed.

Let the slaw chill in the refrigerator for 30 minutes to 2 hours to enhance flavors and texture.

Before serving, give it a final taste and adjust seasoning if necessary.