Place the coconut sugar and water in a medium saucepan over medium heat. Bring to a gentle boil, stirring until all the sugar has dissolved. Let the mixture boil for 2-3 minutes.
Whisk in the coconut milk until fully combined. Reduce heat and let the mixture simmer for 10-15 minutes or until it thickens. (The mixture will thicken slightly more as it cools.) Remove from heat and stir in the vanilla and salt. Let the mixture cool in the pan for 10 minutes, then pour into a glass jar with a lid. Let cool completely and store, covered, in the refrigerator for up to 2 weeks.
To reheat the sauce for serving, remove the lid from the jar and microwave for a few seconds or remove the lid from the jar and place the jar in a pan of simmering water until warm.