In a small bowl, whisk together the soy sauce, dark soy sauce, Chinese vinegar or rice vinegar, sugar, sesame oil, water, and cornstarch. Set the sauce aside.
2 tbsp low sodium soy sauce, 1 tbsp Dark Soy sauce, 1 tbsp Chinese black vinegar, 2 tsp sesame oil, 1 ½ tbsp sugar, 2 tsp cornstarch, ¼ cup water