1. Place mayonnaise, parmesan and apple cider vinegar in a small bowl, stir to combine well.
2. Cut the broccoli head into small-mouthful sized florets.
3. In a large bowl combine broccoli, almonds, cranberries, pumpkin seeds, sunflower seeds, onion and lemon zest.
4. Stir through mayonnaise mixture, and stir well to ensure everything is well coated. Season with salt and pepper to taste.
5. Place in fridge overnight (or a minimum of 2 hours).
6. Remove from fridge 30 minutes before serving, so that salad is served at room temperature.