Stir together the
flour, granulated sugar, vanilla sugar, lemon zest,
and salt in a medium bowl.
Add the butter,
distributing the pieces evenly over the mixture. Use
a pastry blender to cut in the butter until the
mixture resembles coarse crumbs.
Make a well in the
center and add the egg, mixing until a dough is
formed. Turn out onto a lightly floured surface,
working in the candied cherries, candied peel, and
nuts.
Knead until
smooth. Return the bowl, cover with plastic wrap,
and refrigerate for 30 minutes.
Preheat the oven
to 350°F/180°C/gas 4. Line two cookie sheets with
parchment paper. Roll out the dough to a thickness
of 1/s inch (1 cm).
Use a 2 1/2 inch
(6cm) round or diamond-shaped cutter to stamp out
shapes. Use a metal spatula to transfer the cookies
to the prepared cookie sheets, spacing 1 inch
(2.5cm) apart.
Mix the egg yolk
and water in a small bowl. Brush the cookies with
the egg yolk mixture. Bake for 12-15 minutes, or
until lightly browned.
Cool the cookies
on the sheets for 10 minutes. Use a metal spatula to
transfer to racks to cool.