Whisk together the sugar and cornstarch in a wide saucepan. Stir in the water and orange juice; bring to a boil over medium-high heat, whisking until thickened. Stir in the cherries and orange zest, return to a boil, then reduce heat, and simmer for 10 minutes. While the cherries are cooking, spoon the ice cream into serving bowls.
Remove the cherries from the heat, and stir in the cherry extract. Pour in the brandy, and ignite with a long lighter. Gently shake the pan until the blue flame has extinguished itself. Spoon the cherries over the bowls of ice cream.