Begin by adding water to a large pot. Add the chicken tenderloins into the water. Bring the water to a boil.
Once the water has come to boiling, reduce the heat to low and cover the pot. Cook for 8 to 10 minutes. Do not overcook or the chicken can become rubbery. The chicken should register at 165 degrees with a meat thermometer. You will also be able to tell it is done when you shred it.
Once the chicken is done, remove it from the water and let it cool. Use two forks or use a stand or hand mixer to shred the chicken in a large bowl. I find that using a mixer is best because it is quicker and it helps get the chicken very fine.
Next, use your food processor to dice your celery and onion into fine pieces.
Add the mayonnaise, celery, onion, and seasonings to the shredded chicken. Stir well and then serve.