Blend lemons, sugar, ginger beer and mint leaves in a blender until leaves are finely chopped and sugar granules are dissolved. Strain through a fine strainer, reserving some of the pulp for garnish.
Add enough ice cubes to fill blender then pour juice inside blender and blend until smooth. Serve immediately. Add lemon and mint pulp on top to garnish.
Cook's Notes
Ginger beer substitute: You can use 1 1/2 cups water with 2 inches of ginger in place of the ginger beer.