Prepare the Vegetables:
If using fresh broccoli, trim and peel the broccoli stems, then shred them using a box grater or food processor. Combine the shredded broccoli, carrots, purple cabbage, and green onions in a large bowl.
Make the Dressing:
In a small bowl, whisk together mayonnaise, apple cider vinegar, honey, Dijon mustard, garlic powder, salt, and pepper until smooth. Adjust the seasoning to taste.
Toss the Slaw:
Pour the dressing over the vegetables and mix well to coat evenly. Add the dried cranberries and sunflower seeds or almonds, and toss gently to combine.
Chill and Serve:
Refrigerate the broccoli slaw for at least 30 minutes to allow the flavors to meld. Serve cold as a side dish or topping.