My Key lime sugar cookies combine the bracing bite, tantalizing citrus aroma, and sweet tartness of a good Florida Key lime pie. They also have a very crisp texture and slight cunch from the sprinkling of sugar on top. (You can use lime-colored sugar, if desired.)–Nancy Baggett
In a small bowl, combine the oil and lime zest. Let stand, covered, for at least 30 minutes and up to several hours. Microwave the lime juice in a 2-cup microwave-safe measure on high power for 2 1/2 to 5 minutes, stopping and checking after 2 minutes, then every 30 seconds, until the lime juice is reduced to 2 1/2 tablespoons; it’s normal for the juice to darken in color slightly. (Alternatively, heat the juice in a small nonreactive saucepan over medium heat until reduced to 2 1/2 tablespoons.) If the juice is inadvertently reduced to less than 2 1/2 tablespoons, add enough water to yield 2 1/2 tablespoons. Let cool to room temperature.
In a medium bowl, stir together the flour, baking soda, baking powder, and salt.
In a large bowl with a mixer on medium speed, beat together the oil mixture and granulated sugar until well blended. Add the butter, beating until light and fluffy, about 2 minutes. Beat in the lime juice, vanilla, and lemon extract until well blended and smooth.
Gradually beat or stir in the flour mixture to form a smooth dough. If the dough seems soft, let stand for 5 minutes to firm up slightly. If it seems dry, stir in up to 1 tablespoon water.
Divide the dough in half. Roll out each portion between sheets of baking parchment or wax paper until a scant 1/4 inch thick. Occasionally check the underside of the dough during rolling and smooth out any wrinkles. Stack the rolled portions (paper still attached) on a baking sheet. Refrigerate for about 30 minutes or freeze for about 15 minutes, or until cold.
Position a rack in the middle of the oven and preheat to 350°F (175°C). Grease several baking sheets or coat with nonstick spray. Working with one portion at a time and keeping the other refrigerated, gently peel off the top sheet of paper, then pat loosely back into place so it will be easy to remove later. Invert the dough and peel off the second sheet.
Using a 2 1/4-inch round cutter, cut out the cookies, then cut each round in half with a sharp knife. If at any point the dough softens too much to handle easily, transfer the paper and cookies to a baking sheet and refrigerate or freeze until firm.
Using a spatula, transfer the cookies to the baking sheets, spacing them about 1-inch apart. Re-roll any dough scraps. Continue cutting out the cookies until all the dough is used. Generously sprinkle the cookie tops with the decorating sugar.
Bake one sheet at a time for 7 to 11 minutes, or until the cookies just begin to brown at the edges. If necessary, reverse the sheet from front to back halfway through baking to ensure even browning. Using a wide spatula, immediately transfer the cookies to a wire rack. Let cool completely.
In a small bowl, stir together 1 1/2 cups powdered sugar and 2 1/2 tablespoons lime juice until well blended and smooth. If desired, stir in the yellow and green food color. If necessary, stir in more sugar or juice to yield a piping consistency (stiff enough to hold its shape but soft enough to pipe through a fine tip).
Place the icing in a paper-decorating cone or pastry bag fitted with a fine writing tip. Space the cookies slightly apart on a rack set over baking parchment or wax paper. To suggest lime slices, pipe a thin line around the perimeter of each cookie, then add “segments” by piping a dot in the center and 7 thin spokes radiating out from the dot to the perimeter. Let stand until the icing sets, at least 30 minutes. The cookies will keep, stored airtight, at room temperature for up to 2 weeks or frozen for up to 2 months.