01 - Combine water, granulated sugar, sliced fresh ginger, rosemary sprig, and thyme sprig in a small saucepan. Place over medium heat and bring to a gentle simmer, stirring continuously until the sugar completely dissolves. Allow the mixture to simmer for 3 minutes to extract the herbal flavors. Remove from heat and let cool completely to room temperature. Strain the syrup through a fine-mesh strainer, discarding the solids.
02 - In a pitcher, combine the freshly squeezed lime juice with 1/2 cup of the cooled ginger-herb syrup. Stir thoroughly to ensure the flavors are well incorporated.
03 - Fill two serving glasses with ice cubes. Pour the lime-syrup mixture evenly into each glass, dividing it between the two servings.
04 - Top each glass with sparkling water, pouring gently to maintain carbonation. Stir lightly with a bar spoon to combine the layers without losing the fizz.
05 - Finish each drink by placing a fresh rosemary sprig and a lime wheel on top of the ice. Add fresh cranberries for a festive touch if desired. Serve immediately while chilled.