For the buttermilk brine: Drain the brined chicken and rinse out the bowl it was brined in. Return the chicken to the bowl and pour the buttermilk over. Add the paprika, tomato powder, chervil, parsley, sage, pepper and salt. Cover and refrigerate for 8 to 12 hours.
For the fried chicken: Preheat enough lard to come three-quarters up the side of a large iron skillet to 300 degrees F. Drain the chicken on a wire rack, and discard the buttermilk.
In a medium bowl mix the paprika, tomato powder, chervil, parsley, sage, pepper and salt.
Put some of the flour mixture and some of the chicken pieces in a plastic resealable bag and shake until the chicken is well coated. Shake each piece of chicken to remove any excess flour. Fry the chicken until cooked through and crispy. Season the chicken with salt as soon as each piece come out of the fryer. Repeat the process for the remaining flour mixture and chicken pieces.
Caramelize the onions in large skillet or frying pan with some butter. Add the carrots, celery and chicken bones to the skillet. Coat with the flour, and then add the chicken stock. Cook until reduced by half or until you achieve a thicker texture.
Pour the gravy through a strainer and serve with the fried chicken.