Place the chicken tenderloins on a cutting board and pat them completely dry with a paper towel. Removing surface moisture is an essential step, as any dampness will cause the wet batter to slide right off the meat during frying.

Fill a deep-fryer, large Dutch oven, or heavy-bottomed pot with at least 3 inches of your high-heat frying oil. Heat over medium-high heat until a deep-fry thermometer reads between 360°F and 375°F.

In a large mixing bowl, combine the all-purpose flour, cornstarch, baking soda, baking powder, kosher salt, sugar, onion powder, and garlic powder. Whisk the dry ingredients firmly together to distribute the leaveners and spices evenly.

Slowly pour the cold water (or cold club soda) into the dry mixture. Whisk gently just until the ingredients combine into a smooth batter that resembles thin pancake batter. Do not over-mix; leaving a few tiny, stubborn lumps is perfectly fine and actually helps create a crunchier texture.

Set your batter bowl right next to the hot oil. Working with 2 or 3 pieces of chicken at a time to keep from crowding the pot, drop the planks straight into the batter, turning them over to ensure they are coated completely.

Lift a battered chicken plank out of the bowl using tongs or your fingers, allowing the heavy excess batter to drip back into the bowl for a few seconds.

The Baker's Trick: Carefully and slowly lower the chicken tenderloin into the hot oil. Hold onto the tip of the chicken for the first 2 to 3 seconds as it hits the surface before releasing it entirely. This brief pause allows the batter to flash-fry and seal around the outside first, preventing the chicken from sinking and fusing to the metal bottom of your frying basket or pot.

Deep-fry the chicken planks for about 3 minutes per side (roughly 5 to 6 minutes total). Turn them occasionally using a slotted spoon. The planks are finished when the batter puffs up completely, floats easily to the surface, and turns an even, beautiful golden-brown color.

Use a slotted spoon or spider wire mesh to scoop the hot chicken out of the oil. Transfer the planks onto a wire cooling rack set over a baking sheet to drain any pooling surface oils. (Avoid draining them on paper towels, as the trapped steam beneath the chicken can quickly make the bottom coating soggy).

Sprinkle with an extra tiny pinch of kosher salt while they are still steaming hot, let them cool for 2 minutes, and serve immediately with hushpuppies, french fries, and plenty of tartar sauce or malt vinegar.