First, separate the egg whites and egg yolks into separate bowls. Pour corn oil and milk into the egg yolk bowl and beat well with a hand whisk, then sift in the low gluten flour and mix with a spatula to form a batter without dry powder. Sift the batter once. Add the white vinegar into the egg whites, add the sugar in three parts, and beat with an electric whisk until the meringue is formed. Pour in one-third of the sugar and beat with an electric mixer on medium-low speed until coarse peaks form, then pour in one-third of the sugar and beat on high speed until the egg whites turn white and streaks appear, then pour in one-third of the sugar and continue to beat on high speed, and when you lift up the mixer, a small curved hook will appear, and then turn the mixer upside down until the egg whites don't drip. Spoon one-third of the meringue into the bowl of egg yolk paste, mix well, then pour all the egg yolk paste into the bowl of meringue and mix well. Pour into an eight-inch round mold, vigorously shake out the air bubbles, wrapped in a layer of plastic wrap, steamer pot boiling water, put the mold, cover the lid, medium-low heat steam 40 minutes.