In a large bowl, combine 1/2 cup of the soy sauce, 1/2 cup of the macadamia nut oil, the mirin, garlic, 1 tablespoon of the ginger, the salt, white pepper, cornstarch, and 1 1/2 teaspoons of the brown sugar; mix well. Add chicken and marinate overnight. In a large skillet or wok, heat the remaining 3 tablespoons macadamia nut oil. Add chicken, including marinade, and the remaining 2 tablespoons ginger. Stir-fry until chicken is brown. Add onion, mushrooms, carrots, celery, bamboo, watercress, and green onions; cook for 1 minute. Combine the remaining 3/4 cup soy sauce, the remaining 1/2 cup brown sugar, and the chicken broth; add to mixture. Stir in long rice; top with tofu. Cover and simmer for 5 minutes. Makes 8 to 12 servings.
