MIX flour and baking soda in large bowl; CUT IN butter with pastry blender until mixture resembles coarse crumbs.
BEAT egg yolks and sugar in mixer bowl with whisk attachment on high speed until light and fluffy, 5 minutes. BEAT IN sour cream, lemon juice and lemon peel. ADD yolk mixture, 1/3 at a time, to flour mixture, stirring just until combined after each addition. REFRIGERATE, covered, until firm, 30 to 60 minutes.
HEAT oven to 350°F. Work with 1/4 of the dough at a time, keeping remaining dough refrigerated. ROLL pieces of dough on lightly floured surface into 6 x 1/2-inch ropes. SHAPE as desired; place on ungreased baking sheets.
BAKE in 350°F oven until lightly browned, 12 to 14 minutes. COOL on baking sheets 5 minutes. REMOVE to wire racks; cool completely.
Chilled dough is easier to handle and holds its shape better.
Add lemon juice and peel according to personal taste. Remember to grate the peel before juicing the lemons.