Add the garlic and stir-fry for just 10 seconds or so, then immediately add in the bell peppers and onion. Saute just a minute, then add the sauces one by one in the center of the wok--the ketchup, tamari, chili sauce, vinegar, maple syrup and powdered ginger. Mix together quickly and then add four cups of water to the wok. Bring to a boil and taste the sauce. If needed, add salt.