In a large bowl combine 1 1/2 cups buttermilk, 1/4 cup pickle juice or vinegar, 1 tablespoon hot sauce, 1 1/2 tablespoons garlic granules, 1 1/2 tablespoons onion granules, 2 teaspoons paprika, 2 teaspoons coarse salt, and 1 teaspoon black pepper.
Add the chicken tenders to the marinade, coat well, cover, and refrigerate for 2 to 24 hours.
Whisk together the flour, cornstarch, baking powder, 2 teaspoons garlic granules, 2 teaspoons onion granules, 2 teaspoons paprika, 3 teaspoons coarse salt, and 1 teaspoon ground pepper in a wide shallow bowl; set aside.
In a second wide bowl whisk 4 large eggs with 1/2 cup buttermilk and the remaining 1 teaspoon salt and 1/2 teaspoon pepper to make the egg wash; set aside.
Heat oil in a 4- or 5-quart pot until it reaches 375°F, using a candy or instant-read thermometer to monitor temperature.
Remove a few tenders from the marinade, drain excess, then dredge in the seasoned flour, pressing to coat thoroughly.
Shake off excess flour, dip the coated tender into the egg wash to fully cover, drain excess egg, then dredge again in the flour mixture pressing to adhere a second time. Place on a wire rack set over a sheet tray and rest up to 15 minutes; repeat with remaining tenders.
Fry 4 to 6 tenders at a time, lowering them gently into the 375°F oil (temperature will drop to about 350°F). Cook 3 1/2 to 4 minutes, turning once or twice, until golden brown and cooked through.
Transfer cooked tenders to a wire rack to drain while you finish remaining batches; keep oil temperature near 350–375°F between batches.
Serve hot with optional dipping sauces such as ranch, blue cheese, or honey mustard.
