Preparation (Marinade):

1. In a large bowl, mix the buttermilk, smoked paprika, cayenne pepper, garlic powder, onion powder, marjoram, salt, and black pepper.
2. Add the chicken pieces to the marinade, ensuring they are fully coated. Cover and refrigerate for at least 4 hours, preferably overnight.

Coating:

1. In another bowl, combine the plain flour, cornflour, smoked paprika, ground cumin, marjoram, cayenne pepper, salt, and black pepper.
2. Remove the chicken from the marinade, allowing excess buttermilk to drip off, and coat each piece thoroughly in the flour mixture. Press the flour mixture onto the chicken to ensure it sticks.

Frying:

1. Heat the vegetable oil in a large, deep pan over medium heat until it reaches 170°C. Use a thermometer for accuracy.
2. Fry the chicken in batches to avoid overcrowding, cooking for 12-15 minutes, turning occasionally, until the coating is golden brown and the internal temperature of the chicken reaches 75°C.
3. Transfer the cooked chicken to a plate lined with kitchen paper to drain excess oil.