In a medium bowl combine the flour, baking soda, lemon zest, coriander and poppy seeds. Mix well with a wire whisk and set aside.
In a large bowl cream together the butter and sugar with an electric mixer at medium speed until the mixture forms a grainy paste.
Scrape down the sides of the bowl (this ensures that the butter and sugar are thoroughly blended to provide a consistent base for the remaining ingredients). Then add the egg yolks, egg, and lemon extract. Beat at medium speed until light and fluffy.
Drop by rounded teaspoonfuls onto an ungreased cookie sheets, 2 inches apart. Bake at 300° for 23-25 minutes or until cookies are slightly brown along the edges. Immediately transfer the cookies with a spatula to a cool surface.