In a 12-in. skillet heat oil over medium-high heat until hot. Sprinkle steak with five-spice powder and 1/4 tsp. salt; add to skillet. Cook 3 minutes or until just browned, stirring occasionally. With slotted spoon, transfer to a medium-sized bowl.
Add peppers, onion, 2 Tbsp. water, and a pinch of salt to the skillet. Cover and cook for 5 minutes, or until slightly softened, stirring occasionally.
In a small bowl, whisk together sugar, soy or teriyaki sauce, cornstarch, 3 Tbsp. water, and 1/4 tsp. freshly ground black pepper until smooth. Add to skillet; heat to simmering. Simmer 1 minute or until thickened. Add beef and any accumulated juices to skillet. Cook 1 minute or until beef is heated through. Serve with rice.