Mix 1 cup of buttermilk, 1½ teaspoons of salt, ¼ teaspoon of cayenne pepper, ¼ teaspoon of garlic powder, and ¼ teaspoon of paprika. Add 900g of chicken tenderloins, cover, and refrigerate for 4-24 hours.
Whisk 1½ cups of all-purpose flour, 1½ teaspoons of baking powder, 1 heaping teaspoon of salt, ¾ teaspoon of black pepper, ¾ teaspoon of garlic powder, and ¾ teaspoon of paprika.
Drizzle in 3 tablespoons of buttermilk and mix with a fork until the flour forms small clumps.
Heat ¾in / 2cm of vegetable oil in a large, high-sided pot to 350°F / 175°C. Lift the chicken from the marinade, let the excess drip off, and press it into the flour mixture to coat.
Fry in batches for a few minutes per side, until golden and the chicken reaches 165°F / 74°C. Drain on paper towels.
