In medium bowl combine flour, baking powder and salt; set aside. In large bowl cream butter, sugar and peel until light and fluffy. Beat in egg and lemon juice until well mixed (mixture may appear curdled). Stir in flour mixture until blended. Shape sough in two 5 cm diameter rolls. Wrap tight; chill 4 hours or until firm. With sharp, thin knife, using sawing motion, slice 0 cm thick. Add optional decorations. Place slices 3 cm apart on lightly greased baking sheet. Bake in preheated 365 degree oven 8-10 minutes or until golden on bottom. Remove to rack to cool. HOLIDAY DECORATION: To make tree stencil, fold 8 cm square heavy-gauge paper in half. Using fold as center, cut out a design that does not exceed 2x2 inches. Place pattern on cookie; sprinkle cut out with colored sugar. Place cinnamon candy on top/