• Step 1: In a large bowl, combine the cooked and diced chicken, halved grapes, diced celery, and diced red onion.
• Step 2: In a separate small bowl, whisk together the mayonnaise, lemon juice, and Dijon mustard until well combined.
• Step 3: Pour the dressing over the chicken and grape mixture and gently toss to coat evenly.
• Step 4: Season the salad with salt and pepper to taste, adjusting the seasoning as needed.
• Step 5: Cover the bowl and refrigerate the chicken and grape salad for at least 30 minutes to allow the flavors to meld together.