In the bowl of an electric mixer fitted with a paddle attachment, cream the butter and sugar on medium speed until smooth, about 2 minutes. Turn mixer to low and add the egg, vanilla extract, lemon zest and lemon juice. Mix well.

In a separate large mixing bowl, whisk together the flour blend, baking powder and salt.

Turn the mixer to low and add the sweet rice flour mixture to the butter mixture and mix well. Shape the dough into 2 flattened disks, wrap with plastic wrap and refrigerate for at least 1 hour. Dough can be frozen at this point for future use.

Preheat oven to 350 degrees. Line baking sheets with either parchment paper or silicone baking mats.

Lay a piece of waxed or parchment paper on a work surface. Sprinkle with some flour blend, place one dough disk on top, sprinkle that with some flour blend and top with another piece of waxed or parchment paper. Roll dough to a thickness of about ¼ inch. Just before you get the dough rolled to the desired thickness, remove the top layer of waxed paper, spread a little more flour blend over the top of the dough and then flip the dough (waxed paper and all) over, remove the top layer of waxed paper, sprinkle with more flour and do your final roll or two. This will make it easier to remove the cookies once cut. Cut out cookies into desired shapes and place on prepared pans, spacing about 1 inch apart. Brush off any excess flour. To keep the edges of the cookies sharp, refrigerate for 15 minutes before putting in the oven. If you do not plan to ice the cookies, sprinkle them with sugar before baking. Repeat with remaining dough disk. Left over dough can be re-rolled once; gather up scraps, form into a disk and refrigerate for 30 minutes at least before rolling.

Bake for about 10 minutes. Do not let the cookies brown.

Let cool on pan for 10 minutes and then remove to a wire rack with a spatula to cool completely before icing.

In a small bowl, mix together the powdered sugar with lemon juice. Beat in the corn syrup or agave, starting with 6 teaspoons and adding more if it is too thick. Use it thick for outlining and adding detail to the cookies.

Separate icing into small bowls and color with food coloring to desired shades. Spread or pipe on cookies and allow icing to set.