In a large bowl, whisk together buttermilk, 1 teaspoon salt, 0.5 teaspoon pepper, garlic powder, and smoked paprika.
Submerge chicken tenderloins in the buttermilk mixture, cover, and refrigerate for 30 minutes.
In a separate shallow dish, combine flour, cornstarch, cayenne pepper, and the remaining salt and pepper.
Heat vegetable oil in a heavy-bottomed skillet or Dutch oven to 350°F (175°C).
Remove chicken from the buttermilk, allowing excess to drip off, then dredge thoroughly in the flour mixture, pressing firmly to ensure coating adhesion.
Fry chicken in batches for 3 to 4 minutes per side until the crust is golden brown and the internal temperature reaches 165°F (74°C).
Transfer fried tenders to a wire rack set over a baking sheet to drain and preserve crispness.