In a small saucepan, bring 2 cups sugar and 1 1/2 cups water to a simmer over medium heat, stirring until the sugar is dissolved; remove from the heat. Place 2 cups fresh cranberries in a medium, heatproof bowl and pour the hot liquid on top; let cool to room temperature. Cover with plastic wrap and refrigerate overnight. Using a food processor, pulse 1/2 cup sugar with the seeds scraped from 1 vanilla bean until superfine; transfer to a shallow dish. Strain the cranberries with a slotted spoon, add to the sugar and roll to coat. Transfer the sugared berries to a parchment-lined baking sheet and let stand until set, about 1 hour. Store in an airtight container for up to 2 weeks.