Put the egg white in a clean, dry bowl and whisk it until lightly foamy, gradually adding the powdered sugar about 1 tbsp at a time.

One egg white takes 150 to 200g of powdered sugar - use consistency as your guide. Whisk until the mixture is thick, glossy white and holds its shape, and add a drop of lemon juice at the end.

Cover the icing with a damp, wrung-out cloth and let it rest for an hour to mature, so the sugar grains fully dissolve.

Divide the icing by color and tint it. For outlining, pipe the needed amount into a piping bag right away - this is the thickest consistency.

For flooding, stir a little boiled water into the tinted icing until it reaches the right consistency: it should pour smoothly off a spoon, like thin yogurt or sour cream.

I recommend making both outline and flood consistencies for each color. Divide the icing into bags - and you're ready to decorate!