Beat the butter, sugar and lemon rind
together until pale and fluffy. Beat in the egg yolk, and then sift in
the flour and the salt. Knead together to form a smooth dough. Wrap and
chill for 30 minutes.
Preheat the oven to 190oC/375oF/Gas
5. On a lightly floured surface, roll out the dough to 3mm thick.
Using a 6cm fluted cutter, stamp out
as many biscuits as you can, with the cutter dipped in flour to prevent
it from sticking to the dough.
Transfer the biscuits on to lightly
greased baking sheets. Mark the tops lightly with a 2.5cm holly leaf
cutter and use a 5mm plain piping nozzle for the berries. Chill for 10
minutes, until firm.
Meanwhile, put each egg yolk into a
small cup. Mix red food coloring into one and green food coloring into
the other.
Using a small, clean paintbrush,
carefully paint the colors on to the biscuits.
Bake for 10-12 minutes, or until they
begin to color around the edges.
Let them cool slightly on the baking
sheets, then transfer to a wire rack.