Combine the poppyseeds with 1 cup of water and let soak for 2 hours.
Dry Mix
In a bowl, sift together the cake flour, sugar, baking powder, and salt.
Wet Mix
Combine the egg yolks, oil, and vanilla in a small measuring cup, whisking lightly to break up the yolks.
Form a well in the dry mix and add the poppyseeds (with water) and the wet mix.
Whisk to combine.
Egg Whites
Beat the egg whites and cream of tartar until stiff peaks form. This step is very important, as the egg whites must be at the stiff peaks stage for the cake to rise properly.
Add the above mix to the egg whites and fold in until fully incorporated.
Baking
Pour batter into an un-greased angel food cake tin and bake for 50 minutes at 325°F.
Bake for an additional 10-15 minutes at 350°F, until a skewer comes out clean.
Turn pan upside down to fully cool.
On fully cooled, combine the glaze ingredients until you have the desired consistency and drizzle lemon glaze over the top of the cake.