1. In a large measuring cup or bowl with pour spout, add the tamari and cornstarch. Stir.
2. Add the rice vinegar, rice wine, sesame oil, brown sugar, ginger, garlic powder, dried onion, stock and scallions.
3. Cook chicken tossed in cornstarch.
4. Pour sauce over the cooked chicken, and stir to combine. Allow it to cook, mostly undisturbed, until the sauce begins to thicken.