In one large bowl, whisk together buttermilk and mustard. In another large bowl, mix together flour, paprika, coriander and garlic powder.Sprinkle salt over chicken wings and drumsticks, then add to the buttermilk mixture. Mix well until chicken is evenly coated. Then, transfer the chicken to the flour bowl and toss again until evenly coated in the herbs and spices.Remove chicken from the bowl onto a tray, and spray all over with olive oil. Spray the basket briefly with the oil to avoid sticking.Heat Philips Airfryer to 200°C. Add half the chicken to the basket in a single layer and cook for 20-25 minutes, turning carefully every five minutes, or until golden brown and crisp. Note: To check that they are cooked through, either cut one open and ensure there is no pink chicken remaining or use a meat thermometer and check the temperature has reached at least 70°C.