1. Mix the water and xanthan gum in a small bowl until well combined.
2. Combine the remaining ingredients in a small saucepan, cooking over medium heat, until they come to a boil.
3. Remove from the heat and whisk in xanthan gum.
4. Bring to a boil once more, whisking constantly, until the sauce starts to thicken.
5. Remove from heat and set aside.
6. Pour into an airtight container, like a mason jar, for later use.