In a large, heavy pot, heat the oil over medium-high heat. Working in batches, sear the chicken, turning once or twice, until browned on both sides, about 9 minutes. Transfer to a plate.

Pour off all but 1 tablespoon fat in the pot and return the pot to medium heat. Add the onion and cook, stirring occasionally, until softened, 3-4 minutes. Add the garlic, the ginger and half of the tangerine zest and stir until fragrant, about 1 minute. Add the broth, tangerine juice, soy sauce, chile-garlic sauce, and star anise and bring to a boil, stirring to scrape up any browned bits from the bottom of the pot. Return the chicken to the pot, reduce the heat to low, cover, and simmer until the chicken is opaque throughout, about 25 minutes.

Transfer the chicken to a platter. Bring the liquid in the pot to a boil over medium-high heat. Stir in the cornstarch mixture and cook just until the sauce thickens slightly, about 30 seconds.

Pour the sauce over the chicken. Sprinkle with the remaining tangerine zest and serve. Serves 4.

Serve over steamed rice, or with crusty bread to soak up the flavorful broth.