Marinate chicken tenders in buttermilk, pickle juice, and jalapeño juice for 12 to 24 hours.
Shake off excess buttermilk and set aside.
In a large bowl, combine flour, cornstarch, paprika, cayenne, black pepper, and 2 tablespoons salt. Dredge tenders in seasoned flour, then shake off excess.
In a countertop fryer or dutch oven, heat canola oil to 350 degrees. Place chicken tenders in a fry basket and carefully lower into oil. Cook for about 3 to 4 minutes, then place on a paper towel-lined plate to drain. Once cool, spread in a single layer on a sheet tray and refrigerate. Once completely cool, cut each tender in half length-wise and chop into 1-inch chunks.
In a large mixing bowl, combine mayonnaise, sour cream, lemon juice, sugar, remaining salt, and hot chicken rub. Stir until it’s a smooth consistency, then add chopped celery and red onion.
Using gloves or a spatula, gently fold chicken pieces into the mixture until all chicken is coated.