Poach the chicken breast in simmering water for 18 to 20 minutes until it reaches 165°F / 74°C at the thickest part, then let it cool completely and dice into bite-size pieces.
Whisk together mayonnaise, sour cream, honey, apple cider vinegar, and black pepper in a large bowl until smooth and creamy.
Add the diced chicken, halved grapes, and chopped pecans to the dressing and toss gently until everything is evenly coated.
Cover and refrigerate for at least 30 minutes to let the flavors blend.
Serve chilled on croissants, over greens, or in a bowl.