Preheat the oven to 325F and line a 9x13" pan with parchment paper.
Whisk together egg yolks, sugar, salt, vanilla, oil, and milk.
Sift in flour and cornstarch; whisk until combined.
In a separate clean bowl, whip egg whites with cream of tartar until stiff peaks form.
Gently fold a third of the egg whites into the batter, then fold in the remaining egg whites.
Bake for ~13-15 minutes, dust with powdered sugar while warm, and roll the cake with parchment paper.
Let the cake cool completely.