Sift the flour into a large bowl, or the bowl of a stand mixer. Stir in the sugar, zest and salt.
Rub in the butter with your fingertips, or the mixer. As there is a large proportion of butter to flour you will form a dough pretty quickly after getting to the breadcrumb stage.
Briefly knead the dough to make it nice and smooth.
Between two sheets of parchment, roll out the dough into a nice neat rectangle and to about 4mm thick and then place in the fridge to rest for 30 minutes
Preheat the oven to 160 degrees Centigrade
Slice 1/2cm wide strips from the chilled dough and place, spaced apart onto a lined baking sheet.
Bake for 12-15 minutes until starting to gain a hint of colour around the edges.
Cool on a wire rack
Once totally cool, dip the tip into the melted chocolate and leave to set. You can sprinkle with coloured sugar crystals at this point if you wish.