In a bowl, combine the buttermilk with salt, pepper, garlic powder, and onion powder. Add the chicken breasts, ensuring they are fully submerged. Cover and refrigerate for at least 2 hours or overnight for best results.

Prepare the Coating

In another bowl, mix together the flour, cornstarch, paprika, salt, and black pepper.

Heat the Oil

In a large pot or deep fryer, heat the vegetable oil over medium-high heat until it reaches 350°F (175°C).

Coat the Chicken

Remove the chicken from the buttermilk marinade, allowing excess liquid to drip off. Dredge each piece of chicken in the flour mixture, pressing down to ensure an even coating.

Fry the Chicken

Carefully place the coated chicken into the hot oil. Fry for about 5-7 minutes per side, or until golden brown and cooked through (internal temperature should reach 165°F/75°C).

Assemble the Sandwich

Remove the chicken from the oil and let it drain on paper towels. Toast the burger buns lightly. Spread mayonnaise on the bottom half of the bun, add the fried chicken, top with lettuce and tomato slices, and drizzle with hot sauce. Place the top half of the bun on and serve immediately.