In a medium mixing bowl stir together the flour, icing sugar, salt and zest.
175 g plain flour, 50 g icing sugar, 1/4 tsp salt, Zest from 1 orange, Zest from 1 lemon
Rub the cold butter into the dry mixture until it is combined and no large chunks of butter remain. The mixture should resemble large breadcrumbs.
150 g vegan block butter*
Bring the cookie dough mixture together into a ball, flatten it slightly and wrap it in eco plastic film or a reusable wrap. Place it in the fridge for 45 minutes.Note: The mixture should come together when squeezed between your fingers. If for any reason it does not then add 1/2 tsp of cold water, mix in and then try again to bring the mixture together. Preheat the oven to 170°C fan (190°C conventional / 375°F / gas mark 5). Line a large baking sheet (or two) with non stick baking paper.
Lightly flour a smooth surface. Roll the dough out to 1/2 cm thick and cut out 16 x 5.5cm (2”) round cookies using a cookie cutter. Re-roll the dough and continue cutting out cookies until you have used the dough.
Sprinkle the tops of the biscuits with caster sugar.
25 g caster sugar
Bake for 11-13 minutes until the edges of the cookies are just starting to colour.
Leave the biscuits on the trays for 10 minutes before transferring them to a cooling rack.