Peel and grate the ginger using a fine grater. Slice the butter into cubes and place in the fridge until needed. Put the flour, brown sugar, cinnamon and 1 pinch of salt in a mixing bowl. Mix with a whisk. Add the ginger, butter and vanilla extract and knead with cool hands until the mixture resembles crumbs. Add the egg yolk and knead quickly to form a smooth dough. Add a little ice water if the mixture is too dry. Shape the dough into a flat ball, wrap the dough in plastic film and leave to rest in the fridge for 30 minutes.
Roll out the dough on a worktop lightly dusted with flour until it is approx. 5 mm thick. Use the cookie cutter to cut out shapes. Place the shapes on a baking tray lined with baking paper. Knead the dough back into a ball, roll it out again and keep cutting out shapes until all the dough is used up. Bake the cookies in the middle of the oven for about 15 minutes until they are brown. Cool on a wire rack.
Sieve the icing sugar and divide over 2 bowls. Add approx. 2 tablespoons of hot water to each bowl. Add the food colouring and stir until you have thick red and green icing. Decorate the cookies with the icing and the sprinkles.
Tip: Make a small cone of baking paper so you can pipe the icing and decorate the cookies neatly. Or use a plastic bag and cut away a small corner.
