In a large mixing bowl, combine the broccoli coleslaw, shredded Napa cabbage, drained pineapple tidbits, and sliced green onions. Ensure the vegetables are well-mixed for even distribution of flavors.

In a separate bowl, whisk together mayonnaise, seasoned rice vinegar, reserved pineapple liquid, coarse ground black pepper, and kosher salt until you have a smooth and creamy dressing.

Pour the dressing over the vegetable mixture and gently toss to coat all the ingredients evenly.

Cover the coleslaw mixture and refrigerate for at least 4 hours, or overnight if possible, to allow the flavors to meld beautifully.

Before serving, give your pineapple coleslaw a good stir to redistribute the dressing and refresh the ingredients.