2. In the bowl of an electric mixer, combine the egg yolks and 1 cup of the sugar. Start the mixer on low speed and gradually increase to high speed. Beat until the mixture is thick, moussy and pale yellow, about 8 minutes. Beat in the lemon zest, lemon juice and poppy seeds.
3. Sift the matzah meal cake flour and potato starch over the yolk mixture, but don't mix.
4. Place the egg whites in a clean mixing bowl. Beat on low speed until frothy, about 2 minutes. Add the cream of tartar and salt. Increase the speed to medium and beat for 2 more minutes. Increase the speed to high and add the remaining sugar gradually over 4 minutes.
5. Whisk the egg yolk-matzah mixture just to mix. Gently fold the whites into the yolk mixture.
6. Spoon the batter into an ungreased 10" tube pan. Bake 50 to 60 minutes, until the cakeis browned and springy to the touch.
7. Immediately invert the pan on th eneck of a bottle until the cake is completely cool. Slide a knife around the pan and unmold the cake onto a round platter.
For the glaze:
8. Sift the confectioner's sugar into a mixing bowl. Add the lemon juice and zest and whisk to mix. The glaze should be thick but pourable. Adjust the consistancy by adding lemon juice if it is too thick and confectioner's suger if it is too thin. Spoon the glaze over the cake. When you are ready to serve, use a serrated knife to cut the cake.