Sift flour and baking powder together.
Beat the 4 eggs until thick and lemon-colored. Add the oil of anise. Add the powdered sugar a little at a time, beating until well mixed. Beat in the dry ingredients alternately with the lemon peel in small portions until thoroughly mixed. Chill the dough 2 hours, or until firm.
Grease cookie sheets lightly and sprinkle with a few anise seeds.
Roll dough ½" thick on a lightly floured board, with a springerle rolling pin. (This is a roller covered with intricate designs and figures which stamps the cookies as you roll. Each design is enclosed in a square or rectangle.) Press the roller heavily on the dough to get a good imprint, and then cut the cookies apart along the border lines stamped between the designs.
Lift the cookies carefully onto cookie sheets. Cover and let stand overnight in the refrigerator.
Bake in a preheated 350° oven for 30 minutes until lightly browned. Remove with a spatula at once onto a rack to cool. When thoroughly cooled, store in a tightly covered crock or jar for at least 10 days. Cookies will keep for months.
If you happen to have almonds on hand, put a sliver or half a blanched almond on each cookie.
NOTES : Oil of Anise is sometimes, but not always, available at grocery stores. Try your favorite pharmacy.