Prep the Chicken: Preheat your oven to 350°F (175°C). Place the chicken breasts and thighs in a bowl. Drizzle with olive oil and toss to coat. Season evenly with granulated onion, black pepper, and sea salt.

Bake: Transfer the seasoned chicken to a baking dish. Cover the dish loosely with aluminum foil. Bake for 25 to 30 minutes, or until the internal temperature of the thickest part of the breast reaches 165°F.

Cool Completely: Remove from the oven and let the chicken rest in its juices for 10 minutes. Transfer the chicken to the refrigerator and chill for at least 1 hour.

Dice the Meat: Once completely cold, use a sharp knife to dice the chicken breasts and thighs into ¼-inch by ½-inch bite-sized pieces.

Mix the Salad: In a large mixing bowl, combine the chilled diced chicken, finely diced celery, and mayonnaise. Stir gently until all ingredients are perfectly combined.

Marinate and Serve: Cover the bowl tightly and refrigerate for 1 to 2 hours (or overnight for the best flavor). Before serving, taste and add a final pinch of sea salt and black pepper if desired. Enjoy!