1. Sprinkle both sides of tilapia fillets with five-spice powder. Combine soy sauce and brown sugar in a small bowl.
2. Heat oil in a large nonstick skillet over medium-high heat. Add the tilapia and cook until the outer edges are opaque, about 2 minutes. Reduce heat to medium, turn the fish over, stir the soy mixture and pour into the pan. Bring the sauce to a boil and cook until the fish is cooked through and the sauce has thickened slightly, about 2 minutes more. Add scallions and remove from the heat. Serve the fish drizzled with the pan sauce.
Tip: Five-spice powder is a blend of cinnamon, cloves, fennel seed, star anise and Szechuan peppercorns. Look for it in the spice section at the market or with other Asian ingredients.