1. Preheat oven to 450°F.
2. Heat oil in a large ovenproof skillet over medium-high heat. Season the chicken with pepper. Add the chicken, skin-side down, and cook, flipping once, until browned on both sides, about 8 minutes. Transfer to a clean plate. Pour off all but 1 tablespoon of fat.
3. Add scallion whites, star anise and ginger to the pan. Cook, stirring, until fragrant, about 30 seconds. Add broth and tamari (or soy sauce). Cook, stirring occasionally, until reduced by about half, 2 to 3 minutes.
4. Return the chicken and any accumulated juice to the pan, skin-side up, and transfer to the oven. Roast until an instant-read thermometer inserted in the thickest part of a thigh without touching bone registers 165°F, about 15 minutes.
5. Transfer the chicken to a clean plate and discard the star anise. Place the skillet over medium-high heat; be careful, the pan handle will be hot. Whisk orange juice, lemon juice and cornstarch and water in a small bowl. Stir into the pan and cook, stirring continuously, until thickened, 1 minute. Spoon the sauce over the chicken and serve with scallion greens and orange wedges.