Heat oven to 400°F (if using dark or nonstick cookie sheet, heat oven to 375°F). In medium bowl, beat butter, 1/2 cup powdered sugar and the lime juice with electric mixer on medium speed until smooth. Beat in flour, salt and 2 teaspoons lime peel.
Shape dough by level measuring tablespoonfuls into crescent shapes, about 2 inches long. On ungreased cookie sheet, place crescents 1 inch apart.
Bake 6 to 10 minutes or until edges begin to brown.
Meanwhile, in small bowl, stir 1 cup powdered sugar and 1 teaspoon lime peel with fork. Roll warm cookies in sugar mixture; place on wire rack. Roll in sugar again.