Creating a chicken salad with leftover chicken is straightforward. Follow these steps to produce a salad bursting with flavor:

1. Prepare Chicken: Start by taking your leftover chicken and shredding it into small pieces.
2. Chop Vegetables: Dice the celery and red onion into small, uniform pieces.
3. Mix Dressing: In a large bowl, combine mayonnaise, Dijon mustard, apple cider vinegar, salt, and pepper. Whisk until smooth.
4. Combine Ingredients: Add the shredded chicken, diced celery, diced red onion, and parsley to the bowl.
5. Fold Gently: Use a spatula to gently fold the ingredients together until everything is well-coated with the dressing.
6. Taste and Adjust: Taste the salad and adjust the seasonings as needed. Add more salt, pepper, or vinegar for extra flavor.
7. Chill (Optional): For best results, let the salad chill in the refrigerator for at least 30 minutes before serving. This allows the flavors to meld nicely.
8. Serve: Serve the salad chilled on a bed of lettuce or as a filling for sandwiches or wraps.

This simple method yields a delicious chicken salad that is sure to please everyone at the table.