Preheat oven to 350'F.
Grease a cookie sheet, or line with parchment paper.
Cream sugar and butter. Slowly add in the flour. Add the lime zest, and the salt.
On a well floured surface roll in to a rectangle and cut into three strips of equal length..
Roll each strip into a tube. The dough will be quite crumbly, just shape it gently.
Cut ¾" pieces from each tube, and roll each piece into a ball.
Pinch the top of the ball to create a raised surface.
Bake for 15 minutes or until they begin to turn golden,
Remove from the oven. Cool slightly and then sprinkle with sugar.