Make a simple syrup: In a pot, add water and sugar. Whisk until well blended. Bring the mixture to a boil over high heat. Reduce heat to low and simmer for 5 minutes. Remove from heat.
Add mint, rosemary, and lemon zest. Steep for 15 minutes. Add the lemon juice, then strain (cheesecloth or fine mesh strainer)
Pour syrup into small 3- or 4-oz. disposable cups. Fill the cups about ¾ full. Freeze until solid.
For best results, remove the icebergs from the freezer and temper at room temperature for 15 minutes before serving.
Variations:
Instead of mint and rosemary, use basil
Use elderflower with lemon
Instead of lemon, use watermelon and lime
Can also combine previously made simple separate syrups from fridge before freezing. For example, Watermelon syrup, mint syrup, basil syrup can be made separately and combined later.