Mix powdered sugar, margarine, egg, vanilla and lemon extract. Stir in flour, baking soda and cream of tartar. Cover and refrigerate at least 3 hours. Heat oven to 375ºF. Divide dough into quarters. Roll each quarter 3/16 inch thick on lightly floured cloth covered board (leave remainder in refrigerator). Cut into desired shapes. Sprinkle with granulated sugar (optional). Place on lightly greased cookie sheet (or use parchment paper). Bake until edges are light brown, 7 to 9 minutes. Makes about 5 dozen. Store in airtight container or freeze. For Stained glass cookies: Either divide dough in half, or make 2 batches. Color half with food coloring (or divide further for more colors). Roll first color out 1/8 inch thick, cut into desired shapes, and place on cookie sheet 1 inch apart. Roll next color, cut and place on top of first color. Then bake as above.