1/2 cup butter, softened
1 cup granulated sugar
1 large egg
1 tablespoon fresh lime juice
Grated rind of 1 lime
1 1/3 cups all-purpose flour
1 teaspoon baking powder
1/2 teaspoon salt
Sugar for sprinkling on cookies

Beat together butter, granulated sugar, and 2 tablespoons lime sugar with an electric mixer until light and fluffy. Beat in egg, lime juice and grated rind.

Sift flour, baking powder, and salt together then add to egg mixture.

Form dough into a 10-inch log and wrap in wax paper. Chill dough until firm, at least 4 hours.

Preheat oven to 375 degrees F. Foil- or parchment-line cookie sheets.

Remove wax paper and cut log into 1/4-inch-thick rounds. Place cookies on prepare cookie sheets. Sprinkle tops with sugar and bake for 10 to 12 minutes, or until pale golden. Remove to wire rack to cool.