Toast sesame seeds 5 minutes in dry skillet, or until fragrant, shaking often.
Set aside.
Plunge orange zest in pot of boiling water.
Simmer 3 minutes, then drain.
Bring orange juice, vinegar, sesame oil, soy sauce, brown sugar, five-spice powder, star anise, and half of orange zest to a boil in skillet over medium heat.
Add tofu, reduce heat to medium-low, and simmer 8 to 10 minutes, or until all liquid has evaporated.
Cook 3 to 4 minutes more, or until tofu cubes are browned, shaking pan occasionally.
Garnish with green onions, sesame seeds, and remaining orange zest.