Preheat the oven to 350 degrees. Place the soy sauce, orange juice, ginger, garlic and cayenne together in a medium mixing bowl and mix well. Place scallion onions, zucchini, red onion and chicken breast in large zip lock plastic baggie and pour marinade into baggie. Seal bag and shake until the chicken breast are well coated with marinade. Place bag in the refrigerator and let marinade for anywhere from 1 hour to 24 hours. Layer each chicken breast into a large baking dish and pour marinade over chicken. Bake for 30 minutes. Place each breast over 1 cup of steamed rice and serve.