Preheat the oven
to I90.C/3751'/Gas 5. Line two baking sheets with
non-stick baking paper. Whisk the eggs, sugar and
lemon rind together with a hand-held electric whisk
until thick and mousse-like: when the whisk is
lifted, a trail should remain on the surface of the
mixture for at least 30 seconds.
Carefully
fold in the flour with a large metal spoon using
a figure-of-eight action.
Place the mixture
in a piping bag fitted with a 1cm plain nozzle.
Pipe into finger lengths on the prepared baking
sheets, leaving room for spreading.
Sprinkle the
fingers with caster sugar. Bake for 6-8 minutes
until golden brown, then remove to a wire rack to
cool completely.