Adjust rack to top position and preheat oven to 425 degrees. Lightly oil a baking sheet. Pat chicken dry with paper towels and season all over with fry seasoning, salt, and pepper. Place seasoned chicken on prepared sheet at least three inches apart. Roast on top rack until golden brown and cooked through, 20-25 minutes. (TIP: if using an air fryer, preheat to 400 degrees. Season chicken as instructed, then coat with nonstick cooking spray; air-fry until browned and cooked through, 15-20 minutes.) Top chicken with smoky mustard and serve (or stash separately and top chicken with smoky mustard just before serving!).