How to Make It
In a large container, combine the Cognac and lemon zest strips. Let the mixture stand at room temperature for 6 to 8 hours. Discard the lemon zest.
In a large saucepan, combine the sugar, cinnamon stick and ginger with 16 ounces of water. Cook over low heat, stirring, until the sugar dissolves, about 3 minutes. Strain the brown sugar syrup and let cool.
In a large punch bowl, combine the infused Cognac, lemon juice and three-quarters of the brown sugar syrup; refrigerate until chilled, about 2 hours. Stir in the Riesling and 32 ounces of chilled water; add more brown sugar syrup to taste. Add the ice and garnish with the freshly grated nutmeg.