In a large bowl, beat butter with a mixer for 30 seconds. Add the powdered sugar beating until is it combined. Mix in the flour until fully incorporated. Stir in the nuts and lime zest.
Shape dough into 1-inch balls. Roll each ball in green colored sugar and place about 2 inches apart on ungreased cookie sheets.
Bake for 15 minutes, until the bottoms are lightly browned. Cool the cookies for 5 minutes on the cookie sheets. Remove warm cookies and roll in additional powdered sugar to coat. Place cookies on wire racks to cool completely.
Cookies can be frozen for up to three months in an airtight container.