Add the tamari or coconut aminos, brown sugar substitute, garlic, rice vinegar, and ginger to a heavy-bottomed pot over medium heat. Mix well to help the sweetener dissolve.
Bring to a boil, then reduce the heat and simmer for 3-5 minutes.
While stirring continuously, add the xanthan gum slowly. Keep mixing for a few minutes until the sauce thickens.
Remove from heat and allow to cool.
This recipe is for 16 servings of teriyaki sauce.Make sure to stir continuously while adding the xanthan gum to avoid clumping.Sauce can be stored in an airtight container in the refrigerator for up to a week.