Place the sugar, kumquat zest, and 1 cup water in a small saucepan, and bring to a boil. Once the sugar has dissolved, reduce heat to low, and simmer 30 minutes. Remove saucepan from heat, strain, and let cool completely.Advertisement
Combine the kumquat syrup, lemons, limes, oranges, star fruit, grapes, white wine, sparkling grape juice, and brandy in a large container. Cover, and refrigerate at least 2 hours or overnight so flavors set. Serve sangria over ice.