Cook chicken breast until completely done, either by poaching, baking, or grilling. Let it cool completely before shredding it into bite-size pieces.
In a large mixing bowl, combine mayonnaise, Dijon mustard, lemon juice, salt, and pepper. Stir until the mixture is smooth and well-integrated.
Add the shredded chicken to the dressing mixture, ensuring each piece gets coated evenly.
Gently fold in the diced pickles, chopped celery, minced red onion, and fresh dill.
If using any optional ingredients, add them now and fold to combine.
Taste the salad and adjust the seasoning with additional salt, pepper, or lemon juice if needed.
Cover the bowl and refrigerate the dill pickle chicken salad for at least 15 minutes before serving to allow flavors to meld.