Heat the sugar and water in a saucepan over medium-low heat. Allow the mixture to cook below a simmer, stirring is not needed, for about 8-9 minutes, or until the sugar is completely dissolved and the liquid is light amber in color.
Immediately transfer to a large bowl and add vanilla and salt. Place coconut oil in a heat-safe bowl and microwave about 15-20 seconds, or until it has completely melted to a liquid. Add the melted coconut oil to the caramel sauce and whisk until all ingredients are well combined.
Allow the sauce to sit and cool for about 20-25 minutes. When the caramel has reached a smooth, thick, syrup-like consistency, whisk again, and serve.
Storage: caramel sauce will last for several days in a covered, airtight container stored in a dry, cool, shaded location. Coconut oil will solidify over time; caramel sauce should be reheated in the microwave for only about 5-8 seconds and stirred before serving.