In a small or medium saucepan, whisk together sifted cocoa powder, sugar, and water over medium heat.
Bring to a simmer, then lower the heat.
Stir frequently as it simmers for about 3 minutes; it shouldn't come to a rolling boil.
Remove from heat and stir in vanilla extract and salt.
Allow to cool, and transfer to a glass jar or bottle.
Chill in the fridge before using for optimal flavor and texture.
Store in an airtight container in the fridge for up to 1 month.
