Make a simple syrup by combining the sugar and 1/2 cup of water in a saucepan and bringing to a boil until the sugar is dissolved. Let cool.
Meanwhile, thinly slice the cucumber into coins. Reserve a few coins for garnish and put the rest into a blender with the cilantro and 1/4 cup of water. Blend until the mixture reaches a liquid consistency.
In a pitcher, combine the simple syrup, cucumber-cilantro blend, and lemon juice with 3 cups of water. Stir until well combined. Pour into frosted, salt-and-sugar-rimmed glasses, adding alcohol if you’re tryna get down, and garnish with the cucumber slices and cilantro sprigs.