-tablespoon water For glazing cookies. Grease several baking sheets and set aside. With a mixer at medium speed, beat the butter in a large mixer bowl until light and fluffy. Beat in the sugar until well blended and smooth. Beat in the egg and lemon peel. With the mixer at low speed, beat in the flour just until evenly incorporated. Divide the dough in half. Place each portion between large sheets of waxed paper. Use a rolling pin to roll out the dough to a scant 1/4 inch thick. Check the undersides and smooth out any wrinkles in the waxed paper. Stack the rolled portions on a tray or baking sheet. Refrigerate for about 20 minutes or until cold and firm, but not hard. Heat the oven to 375F. Working with one chilled portion of dough at a time (keep the other one chilled), peel away a layer of waxed paper. (This makes it easier to lift the cookies from the paper later.) Replace the paper and turn the dough over. Peel of the second layer of paper. Using a 2-inch round or scalloped cutter (or a small juice of sherry glass) cut out the cookies. Use a spatula to carefully lift the cookies from the paper and place them about 1 inch apart on the baking sheets. Reroll the dough scraps between waxed paper; rechill in the refrigerator. Repeat the process with the second portion of dough. Working with a few cookies at a time, brush the tops with the egg yolk-water mixture using a pastry brush or paper towel. Sprinkle the tops lightly with granulated sugar. Repeat until all of the cookies are garnished. Bake the cookies for 6 to 9 minutes or until the top is just tinged with brown and slightly darker at the edges. Let cool on the baking sheets for about 2 minutes. Transfer to wire racks and let stand until thoroughly cool. Store airtight for up to a week. Freeze for longer storage. Makes 50 to 60 cookies. [THE BALTIMORE SUN; November 25, 1990]