Lemon Blueberry Swiss Roll Cake

Preheat oven to 450 degrees F and have the rack at the middle setting in the oven. Grease and line with parchment paper a 12 x 8 baking tray. Grease the parchment paper as well.

Have ready a cooling rack with a damp tea towel spread on top. (This is for rolling the cake up when it comes out of the oven)

In a medium bowl, sift together the flour and the cornstarch. Set aside

Separate two of the eggs. Placing the whites in a medium bowl and the yolks in a large bowl. Add the two additional eggs to the egg yolks. Add 1/2 cup of the sugar and mix on high speed until pale and fluffy and has just about tripled in size. Mix in the vanilla extract for just a few seconds and sift in flour and stir until just combined.

With a clean whisk attachment, beat the egg whites until foamy, about 30 seconds. Add the vinegar and beat until soft peaks form, about another minutes. Next add the sugar and beat on high speed until stiff peaks form.

Fold a small amount of the egg whites into the batter until combined. Add the remaining egg whites and mix until just combined.

Pour into the prepared pan and evenly spread out the batter. Bake for 7-10 minutes or until golden and springs back when touched.

Remove cake from oven and invert on the damp tea towel set over a cooling rack. Remove the tray. Gently remove the parchment paper. Roll the cake up with the tea towel. Leave it to cool completely for a few hours.

Cake will keep covered in the refrigerator up to two days.