Combine all ingredients for teriyaki marinade in a small sauce pan. Bring to a low boil, then a simmer for 10-15 minutes. Mixture will be thin. Use this for marinating.
Using an immersion blender or small food processor, blend well.
To make marinade into a sauce, whisk together cornstarch and water until fully combined. Mix with teriyaki marinade until it becomes glossy. Remove from heat, mixture will thicken as it cools.
If you've tried this recipe, come back and let us know how it was!
*You can chop, mince or grate garlic and ginger. The size has a lot to do with preference. I like my teriyaki sauce to be smooth which requires an immersion blender or food processor. If you are going to blend yours, don't pay as much attention to the size of your chopping. If you don't plan to blend, I highly recommend using a micro grater.