https://www.youtube.com/watch?v=_YYF9vBLzGU

6 lemons
5 C cold water
1 1/4 C white sugar

1. Wash lemons and peel off all the zest using a vegetable peeler. Add the
   zest to a bowl and combine with the sugar. Cover and let sit for 2 
   to 12 hours.
2. Bring water to a boil. Turn off heat and pour in the lemon zest and
   sugar mixture. Stir and let sit until the sugar is completely dissolved,
   about 5 minutes.
3. Pour through a mesh strainer back into the same bowl and discard the zest.
   Let cool to room temperature, about 20-30 minutes.
4. Cut lemons in half and squeeze juice into the bowl of zest juice. Pour
   lemonade into serving pitcher and chill thoroughly.