1. Preheat the oven to 350°F. Lightly grease (or line with parchment paper) a baking sheet.
  2. In a medium-sized bowl, beat together the butter, sugar, salt, and baking powder until well-blended.
  3. Beat in the lime juice, lime oil, sour salt (citric acid), and the egg. Blend in the flour thoroughly.
  4. Roll the dough into 1" balls.
  5. Bake the cookies for 14 to 16 minutes, until the cookies are browned on the bottom.
  6. Remove them from the oven, and cool on the pan for about 10 minutes before transferring to a rack.
  7. Mix together the sugar coating ingredients in a pan or bag.
  8. Gently shake and roll the still slightly warm cookies in the sugar until coated.
  9. Allow the cookies to cool completely, then repeat, coating again with the sugar.
  10. Store, well-covered, at room temperature for up to a week. If you're freezing the cookies, you may choose to recoat the cookies in sugar once they've been removed from the freezer, before serving.

Tips from our Bakers

  • Sour salt (citric acid) is what gives the cookies their sour bite; if you want less tang, use just a pinch.