Step 1

In a medium saucepan, whisk together the cocoa powder and sugar until blended. Add the water and 1/4 teaspoon of the salt, and whisk over medium heat until boiling, stirring constantly.

Step 2

Continue boiling until mixture thickens, about 3 minutes. The mixture will still be fairly thin (it thickens to a syrup-like consistency once cool). Taste and stir in additional salt until dissolved, up to 1/4 teaspoon, if desired.

Step 3

Remove from heat and stir in the vanilla. Cool. Taste again. If it's not sweet enough for you, add a bit more sugar and stir in the warm syrup until dissolved.

Step 4

Store syrup in an airtight glass container in the refrigerator. The syrup should keep, refrigerated, for at least a month.