Fill a cocktail shaker with ice. Add the gin, lemon juice, agave nectar, ginger juice, and a handful of crushed ice ice. Shake for 20 seconds, then strain into two glasses. Top with a splash of sparkling water. Garnish with lemon peel.
Notes
*I like this brand of ginger juice, I usually get it at Whole Foods, Central Market or Wheatsville Coop. It lasts awhile in the fridge and it's great for smoothies as well.