Rinse the cranberries: Rinse the fresh cranberries under cold water and pick out any soft or wrinkled ones. Pat them dry and set aside in a heatproof bowl.

Make the sugar syrup: In a small saucepan, combine the granulated sugar and water over medium heat. Stir until the sugar fully dissolves and the liquid turns clear, about 3 to 5 minutes.

Add optional flavorings: Stir in the orange zest and vanilla extract if using, then remove the syrup from the heat. Let it cool for about 5 minutes so it's warm but not boiling.

Pour syrup over berries: Pour the warm syrup over the cranberries in the bowl and stir gently to coat every berry. The cranberries will float at first, which is normal.

Chill the cranberries: Cover the bowl and refrigerate for at least 4 hours, or overnight for best results. The berries should look slightly translucent at the edges when ready.

Drain the berries: Lift the cranberries out of the syrup with a slotted spoon and let them drain over the bowl for about a minute. Reserve the leftover syrup for sweetening drinks if you like.

Roll in sugar: Spread the sanding sugar on a plate and roll the drained cranberries in it a few at a time until fully coated. Shake off any extra sugar as you go.

Dry the coated berries: Arrange the sugared cranberries in a single layer on a parchment-lined tray. Let them air-dry for 20 to 30 minutes until the sugar shell feels firm, not sticky.

Serve or store: Transfer the candied cranberries to a serving bowl or airtight container. They're ready to eat right away or can be refrigerated until you need them.