Add vodka to it, and you've got Mikes Hard Lemonade! Another Cook's Illustrated recipe. Look for large, slightly soft lemons—they tend to be extra-juicy. Store the lemonade in a covered container in the refrigerator for up to 3 days.
Using potato masher, mash lemon slices and sugar in deep bowl until slices release their juice and sugar begins to dissolve. Stir in water and lemon juice until sugar completely dissolves. Strain out lemon slices and chill or pour over ice before serving.