Place the berry mixture in a deep 8 or 9-inch skillet and bring to a simmer over moderate heat. While berries are cooking make the dumpling dough: In a mixing bowl, stir together the flour, sugar, baking powder, baking soda and salt. Stir in the melted butter. Add enough of the buttermilk to form a soft, sticky dough that is slightly wetter than a biscuit dough. Using a soup spoon, spoon the dough over the fruit, forming small dumplings. Sprinkle the dumplings with the cinnamon sugar. Tightly cover the skillet with the lid or a sheet of foil and steam mixture over medium-low heat, without opening lid, until the dumplings set and the surface is dry when touched with a fingertip, about 15 minutes. To serve: Spoon the warm grunt into serving bowls, and top with whipped cream, ice cream or sweetened yogurt.