Remove the outer leaves from the cabbage and slice it in half. Remove the core, then thinly shred the cabbage using a sharp knife or mandoline. Place the shredded cabbage in a large mixing bowl. Grate the carrots and slice the red onion thinly, then add them to the cabbage along with the chopped parsley.

In a separate bowl, whisk together the halal mayonnaise, apple cider vinegar, honey, Dijon mustard, celery salt, black pepper, and garlic powder until smooth and well combined.

Pour the dressing over the vegetable mixture and toss thoroughly until everything is evenly coated. Cover the bowl and refrigerate for at least 30 minutes to allow the flavors to meld together.

Give the coleslaw one final toss before serving. It's now ready to accompany your favorite main dishes or serve as a refreshing standalone salad.