Add all ingredients (tamari or coconut aminos, maple syrup, rice vinegar, water, ginger, garlic, and cornstarch) to a high-speed blender.
Blend on medium-low speed until no large chunks of ginger or garlic remain and the mixture is well combined — about 30 seconds. It will look pale and foamy — this is normal!
Transfer the mixture to a medium saucepan (large enough for the mixture to boil) and turn to medium heat.
Let the sauce come to a boil and keep an eye on it — it should begin to bubble vigorously and start going up the sides of the pan. This will take about 2-3 minutes.
Once boiling and bubbly, reduce the heat to low and whisk for 5-10 minutes, or until the sauce reaches your desired thickness.
Transfer to a heat-proof container like a glass jar or storage container and let cool.
