Dry Brine the Chicken: Place the chicken breasts on a cutting board and pat them completely dry with paper towels. Sprinkle 1 teaspoon of kosher salt evenly across all surfaces of both breasts. Set the chicken on a wire rack over a plate and refrigerate uncovered for 30 minutes. The salt draws moisture to the surface, then reabsorbs into the muscle fibers, seasoning the meat from the interior and producing a firmer texture that holds up well once chopped.
Poach the Chicken: Place the dry-brined chicken breasts in a medium saucepan in a single layer. Add enough cold water to cover the chicken by 4cm / 1.5in. Add 1 teaspoon of kosher salt, the bay leaf, and the fresh thyme sprigs. Bring the water to 82°C / 180°F over medium heat, which is a gentle simmer with small bubbles breaking the surface but no rolling boil. Maintain that temperature and cook the chicken for 18 minutes until an instant-read thermometer inserted into the thickest part reads 74°C / 165°F and the juices run completely clear.
Rest and Chop the Chicken: Transfer the cooked chicken breasts to a clean cutting board and let them rest for 10 minutes at room temperature. Resting allows the internal juices to redistribute evenly throughout the meat before cutting. Using a chef's knife, cut each breast into 1cm / 0.4in cubes. For a more textured result, use two forks to pull the meat into irregular shreds rather than cutting it. Transfer the chopped or shredded chicken to a large mixing bowl and spread it into a single layer. Refrigerate the bowl for 15 minutes until the chicken reaches room temperature or below before adding the dressing.
Build the Dressing: Combine the mayonnaise, Dijon mustard, fresh lemon juice, celery salt, and smoked paprika in a small bowl. Whisk the mixture with a fork for 30 seconds until fully incorporated and uniform in color. Taste the dressing before adding it to the chicken and adjust the lemon juice by 0.5 teaspoon increments to reach your preferred acidity level. A bright, slightly tart dressing balances the richness of the mayonnaise against the neutral flavor of the poached chicken.
Fold in Mix-Ins: Add the diced celery, minced red onion, and chopped parsley to the bowl of cooled chicken. Pour the prepared dressing over the mixture. Using a rubber spatula, fold the ingredients together with slow, deliberate strokes from the bottom of the bowl upward, rotating the bowl a quarter turn between each fold. Fold for approximately 20 strokes until every piece of chicken is coated and the celery and onion are evenly distributed. Avoid stirring or pressing the mixture, which breaks down the chicken texture and produces a paste-like consistency.
Chill Before Serving: Cover the mixing bowl tightly with plastic wrap, pressing the wrap directly against the surface of the salad to minimize air contact. Refrigerate the Chicken Salad for 30 minutes before serving. The resting period allows the dressing to absorb into the chicken and the flavors of the celery, onion, and herbs to meld into a cohesive, balanced dish.
