Start by gathering your fresh ingredients for the Chicken Waldorf Salad. Dice your leftover roasted chicken, chop the celery, and cut the Granny Smith apples into bite-sized pieces. Halve the red grapes and roughly chop the walnuts. Set aside for easy mixing.

In your large mixing bowl, combine the chopped chicken, celery, apple pieces, halved grapes, and walnuts. Gently fold everything together using a spatula or wooden spoon.

In a separate bowl, whisk together about half a cup of mayonnaise, one tablespoon of Dijon mustard, and the juice of one lemon until smooth and creamy.

Pour the dressing over your delightful salad mixture. Use a gentle folding technique to coat all the ingredients evenly with the dressing.

Just before serving, toss in some freshly chopped mint leaves to the salad for an extra layer of freshness.

Chill the Chicken Waldorf Salad for about 10-15 minutes in the refrigerator. Serve it in bowls, garnishing with a sprinkle of black pepper and a few extra walnut pieces on top.