Wash your lemons. Using a paring knife, remove the skin and pith from your lemons, discard.
If desired, cut each lemon in half and remove seeds. Place whole lemons into your blender with 2 Tbsp granulated sugar (or other sweetener), and 2 cups (470ml) cold water. If you want frozen lemonade, substitute 1 cup ice plus 1 cup water.
Blend for a full minute. Test for sweetness, and add more sugar if desired. Add any add-ins now, blend again for one minute.
Serve over crushed ice. Enjoy!