Prepare the chicken breasts by deboning them and chopping them into bite-sized chunks.
Place them in a large bowl along with the grapes, onions, or celery. Use a wooden spoon to stir and combine them evenly, then refrigerate until the dressing is ready.
To make the dressing, bring a small bowl and add the mayonnaise, vinegar, salt, and pepper.
Whisk the ingredients together by hand to get a homogenous mixture, then wrap the dressing with plastic wrap, and leave it in the fridge.
Once you’re ready to serve, lay some lettuce strands (or full lettuce) in the bottom of the bowl, then add a scoop of the chicken salad in the bowl.
Drizzle some of the dressing over the chicken salad.