In a bowl whisk together flour, baking powder, and salt until well blended. Set aside.
In an electric mixer cream butter and powdered sugar together until smooth. Mix in egg yolk, lime juice and lime zest until everything Is combined. With the mixer on low slowly mix in the flour until just combined.
Roll dough into about 1 inch balls. Place on a lined baking sheet about 1 inch apart, they do not spread very much at all. Bake for 13-15 minutes until cookies are set.
Remove from oven and let cool for 5 minutes. Toss the cookies in powdered sugar while the cookies are still warm. Let cool completely, and then toss in powdered sugar again. Store in an air tight container.