1-First Step: Prepare all ingredients and add them to a medium bowl as completed. Dice the celery, finely chop (or thinly slice) the red onion or scallions, and quarter the grapes if using. Juice the lemon and chop the dill fronds.

2-Second Step: Add the shredded cooked chicken to the bowl. Then add the mayonnaise, or use the combination of plain Greek yogurt and mayonnaise. Add the Dijon mustard and, if using, the celery seeds.

3-Third Step: Stir everything until evenly combined. Keep mixing until the dressing coats the chicken and the veggies look glossy and well distributed.

4-Fourth Step: Season with kosher salt and freshly ground black pepper to taste. Start with a small pinch of salt, taste, then add more if needed. This matters because onion and lemon can vary in intensity.

5-Final Step: Serve immediately, or refrigerate until you are ready to eat. For potlucks, chilling helps the flavors settle so every scoop tastes balanced.