Koji Fried Chicken

• 1,500 g bone-in chicken pieces (split breasts cut in half, drumsticks, and/or thighs), trimmed
• 150 g shio koji
• 110 g firm granular rice koji
• 110 g all-purpose flour
• 110 g cornstarch
• 6 g plus 3 g kosher salt, divided, plus extra for seasoning
• 3 g plus 3 g pepper, divided
• 3.5 g baking powder
• 210 g buttermilk
• 1,300 g vegetable oil

1. 150 g shio koji
2. Combine chicken and shio koji in 1-gallon zipper-lock bag. Press out excess air, seal, and massage bag to evenly distribute shio koji. Refrigerate chicken for at least 8 hours or up to 3 days.
3. Combine koji, flour, cornstarch, 6 g salt, 3 g pepper, and baking powder in blender and blend on high speed until finely ground, about 2 minutes. Transfer koji mixture to large shallow dish. Whisk buttermilk, remaining 3 g salt, and remaining 3 g pepper in large bowl. Working with 3 pieces at a time, dunk chicken in buttermilk mixture, then dredge in flour mixture, pressing mixture onto chicken to form thick, even coating. Place chicken, skin side up, on wire rack set in rimmed baking sheet. Refrigerate, uncovered, for at least 1½ hours or up to 24 hours.
4. 1,300 g vegetable oil
5. Adjust oven rack to middle position and heat oven to 350 degrees F/180 degrees C. Meanwhile, heat oil in large Dutch oven to 375 degrees F/190 degrees C over medium-high heat. Place half of chicken in oil, reduce heat to medium, and fry until first side is deep golden brown, 2 to 3 minutes. Flip chicken and continue to fry until second side is deep golden brown, 2 to 3 minutes longer. (Adjust heat as necessary to maintain oil temperature around 300 degrees F/149 degrees C.) Transfer chicken to second wire rack set in second rimmed baking sheet. Return oil to 375 degrees F/190 degrees C and repeat with remaining chicken.
6. Kosher salt for seasoning
7. Bake chicken until breasts register 160 degrees F/71 degrees C and thighs/drumsticks register 170 degrees F/77 degrees C, 10 to 20 minutes, transferring pieces to serving platter as they come to temperature. Season chicken with salt to taste, and serve.

Cook's Note: This recipe gets better with age. The longer you marinate the chicken (up to 3 days), the better and meatier it gets. And the longer you let the dredge sit on the chicken (up to 24 hours), the better and crispier the crust becomes. We use a fry and then bake method for this chicken to prevent the sugar-rich rice koji in the coating from burning. We’ve tested this recipe using both gram measurements and traditional U.S. volume and weight measurements, so you get to pick the one that works best for you.