Combine paprika, black pepper, garlic powder, oregano, and cayenne in a bowl; mix with fork until combined
Whisk the buttermilk, egg, 1 tablespoon salt and 2 tablespoons of the spice mixture in a large bowl; add the chicken pieces; toss to coat
Transfer the contents of the bowl to a gallon sized plastic bag; refrigerate for 4 hours; flip the bag occasionally to redistribute the contents and coat the chicken evenly
Whisk together the flour, cornstarch, baking powder, 2 teaspoons slat and the remaining spice mixture in a large bowl; add 3 tablespoons of the marinade from the plastic bag; work it into the flour with fingers
Remove one piece of chicken from the bag; allow excess buttermilk to drip off; place the chicken in the flour mixture; toss to coat; continue adding chicken pieces to the flour mixture one at a time until they are all in the bowl; toss the chicken until every piece is thoroughly coated; press the flour onto the chicken with your hands to get a thick layer
Place the oven rack in the middle position; preheat oven to 350F; heat the shortening to 425F in a large skillet or chicken fryer; adjust heat as necessary to maintain the temperature
Transfer one piece of chicken at a time into a fine mesh strainer to remove excess flour; transfer to a wire rack on a baking sheet; place skin side down in pan once all of the chicken is coated
Adjust the heat to maintain the temperature at 300F; fry the chicken until it is a deep golden brown on the first side, 6 minutes; don’t move chicken until it has fried for at least 3 minutes
Carefully flip the chicken with tongs; cook on the second side until golden brown, for 4 minutes
Transfer chicken to a wire rack on a baking sheet; place in oven; cook until the internal temperature measures 150F for the chicken breast, 5-10 minutes
Remove chicken to a paper towel lined plate; season with salt
