Place cabbage + carrot mixture in a large mixing bowl.

In a separate bowl, whisk together mayonnaise, dijon mustard, sugar, apple cider vinegar, celery flakes, black pepper, salt, garlic powder, and onion powder. Add desired amount of dressing to the cabbage, mixing until well-incorporated. I recommend putting about ⅔ of the mixture on and scaling up from there (I like it all, personally, but some want less).

Can be served cold or at room temperature; I prefer it cold.