3/4 cup unsalted butter, room temperature

1 cup confectioner’s sugar

Finely grated zest of 2 limes

2 tablespoons fresh lime juice

1 tablespoon pure vanilla extract

1 3/4 cups plus 2 tablespoons all-purpose flour

2 tablespoons cornstarch

1/4 teaspoon coarse salt

3 or 4 drops of green food color (optional)

Put butter and 1/3 cup confectioner’s sugar in a bowl and mix on medium speed until pale and fluffy. Add lime zest, juice, vanilla and food color. Mix until fluffy.

In a separate bowl, whisk together flour, cornstarch and salt. Add to the butter mixture slowly, mixing on low speed until just combined.

Divide the dough in half. Place each half on an 8-by-12 inch sheet of parchment paper. Roll in parchment to form a log 1 and 1/4 inches in diameter. Refrigerate logs until cold and firm, or for at least one hour.

Preheat the oven to 350 degrees. Remove the parchment from the logs and cut the dough into 1/4-inch thick rounds.

Space the rounds 1-inch apart on parchment paper lined baking sheets. Bake the cookies until barely golden, about 13 minutes; rotating sheets halfway through.

Transfer cookies to wire racks to cool slightly, eight to 10 minutes. While still warm, toss the cookies with remaining 2/3 cup sugar.

Cookies can be stored in airtight containers at room temperature up to 2 weeks.