Teriyaki sauce is a cinch to make:
Soy sauce
Sugar
Minced fresh garlic
Minced fresh ginger
did I forget anything? Probably not.
Bottle and refrigerate. I always have some in the fridge. Keeps and keeps.
BTW, you can keep fresh ginger indefinitely in your freezer. When you need some, just shave some off and return to freezer (in a container or plastic bag, of course).