Red Wine Vinegar Mignonette Granité

In shallow bowl, stir together vinegar, water, shallot, and sugar. Freeze until fully frozen, at least 1 hour or up to 2 days. One hour before serving, place small serving bowl in freezer. To serve, scrape frozen mixture with fork to create ice crystals. Stir in pepper. Transfer to chilled serving bowl; serve or cover and freeze until ready to use.