Break up the egg white with a whisk without beating.

Add the powdered sugar little by little, mixing gently without whipping to avoid forming air bubbles.

Check the icing by testing it on a cake; if it’s too runny, add more sugar.

Add a bit of lemon juice to flavor the mixture.

If, once placed in the piping bag, the icing feels too thick, add a little milk to lighten it.

If you want to store the icing in the fridge, cover it directly with plastic wrap pressed against the surface and refrigerate. Alternatively, place it in a piping bag and seal it well to prevent it from crusting.