Step 1

In a large pot over medium-high heat, bring the water to a boil, then reduce the heat to medium-low so bubbles are just breaking the surface. Add the rosemary sprigs; cover and steep for 45 minutes. Remove the pot from the heat and remove the rosemary sprigs (if necessary, strain the mixture to remove loose leaves). Add the sugar and stir until dissolved. Set aside to cool.

Step 2

Place the lemon juice in a large plastic or glass container. Add the cooled rosemary syrup and stir until combined. Refrigerate until cold. Serve over ice, garnished with lemon balm or mint.