Mix the flour, sugar, cocoa powder and gingerbread spice in a bowl. Add the honey, stir the sodium bicarbonate into the milk and add to the mixture, mix together and knead to form a soft, smooth dough, flatten the dough, wrap it in cling film and chill for approx. 24 hrs.
Knead the dough thoroughly once again, add the flour and knead it in. On a lightly floured surface, roll out the dough to approx. 4 mm thick. Cut out shapes of your choice, place them on a baking tray lined with baking paper, brush with a little milk.
Approx. 10 mins. in the centre of an oven preheated to 200°C. Remove from the oven, allow to cool on a cooling rack.
Lightly beat the egg white with the lemon juice, mix in the icing sugar, transfer to a disposable piping bag, cut off the tip to create a small opening.
Spear a hole through the gingerbread pieces with a wooden skewer. Decorate the gingerbread as desired, leave to dry. Insert a piece of string through the holes and hang from a garland or branch.