Start by examining your leftover protein. Is it still moist, or has it dried out slightly in the refrigerator? This assessment determines everything that comes next. If your chicken is dry, you'll need a bit more mayo to restore moisture. If it's perfectly tender, stick with the ½ cup measurement. Shred or cut your chicken into bite-sized pieces—uniform sizing ensures every forkful tastes the same. This is also when I check for any bones or cartilage that might have escaped initial removal. Takes 5 minutes, prevents regret later.

Place your prepared chicken in a large mixing bowl. Pour the mayonnaise over it and stir gently but thoroughly, making sure every piece of protein gets coated. The mayo acts as a protective barrier that keeps your salad moist and stable for days. This step shouldn't be rushed—take time to work the mayo through so you don't end up with dry pockets when you eat. This is where the transformation really begins, from leftover to creamy, intentional dish.

Now add the apple cider vinegar first. Stir it in completely before adding other ingredients. The vinegar will lighten the mayo slightly and create a more complex base flavor. This is about 2 minutes of gentle stirring, letting everything marry. If you're using the optional Dijon mustard, add it now too.

Add the diced apples, raisins, and walnuts. Fold these in gently with a spatula rather than stirring vigorously. You want to distribute them evenly without breaking down the texture of the apples or crushing the walnuts. The gentle folding motion keeps everything from turning into a mushy mess. This step takes about 3 minutes and is honestly meditative—there's something satisfying about bringing all these elements together.

Taste your creation before adding salt and pepper. Sometimes the chicken, mayo, and apples already provide enough seasoning. Start with ½ teaspoon of salt and a few grinds of pepper, then taste again. This prevents over-salting, which is my biggest leftover transformation mistake. Add a squeeze of fresh lemon juice if you like—it brightens everything and prevents apple browning if you're making this ahead of time.