Add the cold water and fresh lemon juice to a blender.
Add the strawberries, sweetener, and lemon zest if using.
Add the ice cubes on top.
Blend until smooth, icy, and slushy.
Taste and adjust the flavor. Add more sweetener if it is too tart, or more lemon juice if you want a stronger lemonade flavor.
Pour immediately into chilled glasses.
Garnish with fresh mint, lemon slices, or strawberry slices if desired.
Serve right away while cold and frosty.