In a medium saucepan, combine the sugar, water, and salt. Heat over medium heat, stirring until the sugar dissolves completely.
Once the sugar has dissolved, add the rhubarb ribbons to the saucepan. Bring the mixture to a gentle simmer.
Simmer the rhubarb for about 10-15 minutes, or until the ribbons are tender but still hold their shape.
Remove the saucepan from heat and stir in the vanilla extract.
Using a slotted spoon, transfer the rhubarb ribbons to a parchment-lined baking sheet, spreading them out in a single layer.
Allow the rhubarb to cool completely at room temperature, then let it dry for at least 2 hours.
Once dried, the candied rhubarb can be stored in an airtight container for up to 2 weeks.