Preheat oven to 350 degrees F. Line cookie sheets with foil.

In medium bowl combine flour, baking powder and salt; set aside. In a large bowl, cream butter and sugar until fluffy. Add egg and egg yolk, beating until light and creamy. Beat in lime juice and peel until well mixed. Stir in the flour mixture until just mixed. Dough will be soft.

Form dough into 1/2 inch balls. If dough is too soft to handle it can be refrigerated for an hour until it's firm enough to gently shape into a ball. Place on prepared cookie sheet and bake until lightly browned, about 10 to 12 minutes. Transfer to wire rack. While still warm, sift powdered sugar over cookies. Cool completely.