In a large mixing bowl, combine the shredded chicken, diced celery, and halved red grapes. Add any optional ingredients like red onion, fresh herbs, or dried cranberries.
In a small bowl, whisk together the olive oil, lemon juice, and Dijon mustard until well combined. Add honey or maple syrup if using.
Season the dressing with salt and freshly ground black pepper to taste.
Pour the dressing over the chicken mixture and gently toss until everything is evenly coated.
If using Greek yogurt or diced avocado for creaminess, fold it in now.
Sprinkle the toasted sliced almonds on top just before serving.
For best flavor, cover and refrigerate for at least 30 minutes before serving to allow the flavors to meld.