The keys to crispy fried chicken are taking your time and managing temperature. Resting the chicken after you dredge it in flour allows the breading to bind together and dry, making it easier to achieve a crispy crust that doesn't fall apart in the pan. The temperature of the chicken also increases slightly while it rests, which improves the texture of the crust and causes the chicken to cook evenly.
Choose a Small Chicken
Choose a smaller chicken -- about 3 to 3 1/2 pounds, if possible -- if you are cutting up a whole bird. Larger chickens often brown too much before they cook through. Cut the breasts into two pieces so they are small enough to cook through without becoming dry.
Season the Chicken Generously
Season the chicken with salt, ground pepper, herbs and spices, as desired. Garlic powder and onion powder add savory flavors. Sage and thyme complement chicken well if you want an herbed crust. Sweet paprika imparts color and a warm flavor. Cayenne pepper and chili powder add heat to the chicken. Work the seasonings under the skin if you use skin-on chicken pieces.
Soak the Pieces in Buttermilk
Place the seasoned chicken pieces in a large resealable plastic bag. Add buttermilk until all the pieces are sufficiently covered. You need about 1 quart of buttermilk to soak 3 to 4 pounds of chicken. The mild acidity of buttermilk tenderizes chicken, helping the meat retain moisture. Refrigerate the chicken while it soaks for 4 to 24 hours.
Blend Flour with Crispness-Enhancing Ingredients
All-purpose flour works well for fried chicken. But self-rising flour yields a puffier, more craggy crust. Add 1/2 teaspoon of baking powder per cup of all-purpose flour to generate the same results. Add 1 tablespoon of cornstarch or potato starch per cup of flour to improve the crispiness of the crust. Oil and air circulate around starch particles more effectively than they do around flour proteins. Potato starch aids in browning the crust, but cornstarch does not. Season the flour mixture generously with the same herbs and spices you applied to the chicken.
Bread and Air-Dry the Chicken
Pour the excess buttermilk out of the bag. Dredge the chicken pieces in the flour mixture. Do not shake excess flour off the meat. Rest the pieces on a wire cooling rack at room temperature for 1 hour. It is not safe to leave raw chicken sitting at room temperature longer than 2 hours. Air-drying the crust helps it stick to the chicken more effectively. The meat also needs to warm to room temperature so that it fries evenly. Cold chicken lowers the temperature of the fat excessively, which makes it more difficult to create a crispy crust.
Prepare the Pan and Oil
Heat a 2-inch-deep cast-iron skillet or a Dutch oven on medium-high. Cast-iron skillets are superior frying pans because they hold heat well for prolonged periods of time. Use a deep, heavy pan without nonstick coating if you don’t have a cast-iron pan. Pour peanut oil or grapeseed oil into the pan until the oil is 3/4 inch deep. Peanut and grapeseed oils each have very high smoke points, so they are unlikely to smoke or burn as you cook the chicken. Vegetable shortening also has a high smoke point, and it is a suitable alternative to cooking oils. Melt enough shortening to achieve a depth of 3/4 inch.
Fry, Fry Away
Place several pieces of chicken in oil preheated to 350 degrees Fahrenheit, according to a deep-fat frying or kitchen thermometer. Fry small batches of three or four pieces at a time so that air and oil can circulate around the chicken. Turn the chicken with tongs every 1 to 2 minutes to promote even browning.
Test and Rest the Chicken
Remove the chicken from the pan when the meat reaches an internal temperature of 165 F, as indicated on a meat thermometer. Skim flour debris from the pan. Wait until the fat reaches 350 F again before you add the next batch of chicken. Place a clean wire cooling rack on a baking sheet. Rest the cooked chicken on the rack to drain it; paper towels absorb excess oil but cause the crisp breading to soften. Place the baking sheet in a 145- to 165-degree F oven or countertop warmer to keep the chicken warm until you finish cooking the remaining pieces. Chicken must be kept above 140 F to prevent bacteria from growing.