Combine the first 7 ingredients in a large, shallow bowl or dish. Mix in the chili sauce, if using. Add the chicken and turn to coat. Cover, refrigerate and marinate the chicken, turning occasionally, for 4 hours, or overnight.
Preheat the oven to 375 degrees F. Line a large baking sheet with parchment paper. Remove chicken from the marinade and set on the baking sheet. Spoon the marinade in the bowl into a small skillet. Bring to a simmer, and simmer marinade until lightly thickened. Brush the chicken with the hot marinade. Bake the chicken 30 to 35 minutes, or until cooked through. Arrange chicken on a platter, drizzle with pan juices, sprinkle with green onion and serve.