If using a rotisserie chicken, discard the skin and shred or chop the meat into bite-sized pieces. If using chicken breasts or thighs, cook to an internal temperature of 165°F, then let the chicken rest before cutting it up. I like to roast a whole chicken and use some of it for this recipe.
In a large bowl, combine the mayonnaise (or Greek yogurt), dijon mustard, lemon juice, garlic powder, salt, and black pepper. Mix until well combined.
Add the chicken, red grapes, red onion, celery, and fresh herbs to the bowl. Gently toss until everything is evenly coated with the dressing.
Serve immediately or store in an airtight container in the refrigerator for up to 3 days.
