1. Combine chicken, celery, grapes, green onions, almonds (or pecans), and chopped dill in a large bowl, Gently toss to combine.
2. Whisk together mayo, sour cream, lemon juice, salt and pepper to taste.
3. Pour the dressing over the chicken mixture. Cover and refrigerate 1-2 hours for flavors to combine.
4. Serve with lettuce on croissants or toasted bread.