How to cook
Preheat the oven to 356°F (180 °C). Sift together 1/2 cup of powdered sugar and flour, then set it aside. In a large bowl, beat the egg whites, salt and baking powder to snow. Turn the mixer on high and gradually add the remaining 1 1/2 cups powdered sugar.
Beat until the yolks become homogeneous and glossy. Add vanilla and lemon rind. Sift 1/4 of the flour to the egg whites and stir until mixed, but with a spatula.
Add the remaining 3/4 of the flour mixture, in 3 batches, and mix until its absorption. Pour the mixture into a pre-greased baking dish or baking tin with a removable bottom with a diameter of 10″ (25 cm). Put the Angel cake to bake in the oven for 35-40 minutes.
To check if it's ready - press on it lightly with your finger; it needs to rise again. Once cooled, release the finished cake from the form. Serve sprinkled with powdered sugar or glaze, as desired.