4 egg whites

280 g custard sugar

1/2 lemon juice

Beat egg whites with sugar until smooth.
Add lemon juice and beat together until everything is smooth and silky.
Use pastry bag to pipe out mixture onto a tray lined with baking paper (or simply, use spoon to place small scoops of mixture onto a tray).
Put them into pre-heated oven to 100 Celsius degrees and dry for 1 hour, until cookies are dry.