In a glass combine the lemon juice and mint simple syrup. Stir to combine. Top with seltzer (I used a small glass and so used about 1 ounce to top, but you can add more seltzer for an even lighter drink). Garnish with mint leaves and serve immediately.
Recipe by Katherine Martinelli at http://www.katherinemartinelli.com/blog/2011/the-israeli-summer-aka-sparkling-limonana/