Place chicken pieces into a medium bowl.
Combine salt, paprika, black pepper, mustard, garlic powder, onion powder, thyme, basil, oregano, and sage in a small bowl. Reserve 1 teaspoon of seasoning mix and sprinkle remaining seasoning on chicken. Toss to coat evenly.
Combine cornstarch and reserved 1 teaspoon seasoning in a resealable plastic bag; shake to combine. Place chicken pieces into bag, seal bag, and shake to coat evenly. Transfer chicken to a fine mesh strainer and shake to remove excess cornstarch. Let rest for 5 to 10 minutes until cornstarch is beginning to absorb into the chicken.
Preheat air fryer to 390 degrees F (200 degrees C).
Spray basket of the air fryer with oil and place chicken pieces inside, making sure pieces do not overlap. You may have to do two batches, depending on the size of your air fryer. Mist chicken with cooking spray.
Cook for 4 minutes. Shake air fryer basket and spray chicken again with oil so there are no dry or powdery areas. Cook until chicken is no longer pink on the inside, about 4 to 5 more minutes. Serve immediately.