Begin by setting cooling racks over a baking sheet, ensuring that any excess oil can drip off the chicken pieces after frying, keeping them crispy with proper airflow on all sides. Use the textured side of a meat mallet to gently tap the chicken, creating a rough surface that helps the breading adhere better. Next, pat the chicken dry and cut it into small, even-sized pieces.
In a large bowl, mix the sour cream, milk, and salt together. Add the chicken pieces, making sure each piece is well-coated with the marinade. Let the chicken marinate for 30 minutes at room temperature. If you prefer, you can marinate it in the fridge for up to 12 hours; just remember to bring it to room temperature for 30 minutes before frying.
While the chicken marinates, prepare the breading by combining all the breading ingredients in a wide container. I find a 10-inch rectangular Tupperware with a lid works perfectly for this.