Bring a large pot of salted water to a boil. Add the rotini pasta and cook until al dente according to package directions, typically 8-10 minutes.
Drain the pasta in a colander and rinse under cold water to stop the cooking process. Allow to drain completely.
Transfer the cooled pasta to a large mixing bowl. If time permits, refrigerate for 15 minutes to ensure it's completely cool.
Add the pineapple chunks, diced ham, red bell pepper, shredded carrots, and sliced green onions to the bowl with the pasta.
In a separate small bowl, whisk together the mayonnaise, rice vinegar, sugar, salt, black pepper, and grated ginger (if using) until smooth and well combined.
Pour the dressing over the pasta mixture and gently fold with a large spoon or spatula until all ingredients are evenly coated.
Cover the bowl with plastic wrap and refrigerate for at least 30 minutes, though 2 hours is ideal to allow the flavors to meld together.
Before serving, give the salad a gentle toss and taste for seasoning, adding more salt or pepper if needed. If the salad seems dry after chilling, add a tablespoon of mayonnaise thinned with a splash of milk or pineapple juice.
Garnish with chopped macadamia nuts if desired and serve chilled.
