Place the shredded chicken in a large chilled mixing bowl.
In a separate small bowl, whisk together the avocado oil mayonnaise, Dijon mustard, lemon juice, sea salt, and black pepper until fully emulsified.
Add the diced celery, minced red onion, and chopped dill to the chicken.
Pour the dressing over the chicken mixture and use a large spatula to fold until every piece of chicken is evenly coated.
Incorporate the toasted pecans if using for added texture.
Cover the bowl with plastic wrap and refrigerate for at least 30 minutes to allow the flavors to meld and the fats to stabilize before serving.