Toast Almonds: Preheat oven to 350°F. Spread almonds on a baking sheet; toast 3-4 minutes until golden. Cool.
Prep Chicken: Cook raw chicken (400°F for 25 minutes, or boil/shred).
Chop Ingredients: Dice celery, halve grapes, finely chop onion (if using).
Make Dressing: Whisk mayo, sour cream, lemon juice, honey, vinegar, herbs, mustard, salt, and pepper.
Combine: In a large bowl, mix chicken, celery, grapes, almonds, and onion. Fold in dressing.
Rest: Refrigerate 1 hour before serving.
Serve: On toasted sourdough, lettuce wraps, or with crackers.