Mix the flour, lemon zest, matcha and salt in a bowl. Add the butter and rub together using your hands to form an even, crumbly mixture. Beat the egg white, icing sugar and vanilla paste well, add and quickly combine to form a soft dough. Shape into a roll approx. 4 cm in diameter, cover and chill for approx. 1 hr.
Spread half of the pistachios on a sheet of baking paper, lay the dough on top, top with the remaining pistachios then lay the second sheet of baking paper over the top. Roll out the dough between the sheets of baking paper to a thickness of approx. 4 mm, cut out snowflakes, transfer to two trays lined with baking paper.
Bake each tray for approx. 8 mins. in the centre of an oven preheated to 200°C. Remove from the oven, allow to cool a little, then leave to cool completely on a rack.
Combine the icing sugar and lemon juice and use to decorate the stars, top at once with the festive toppers, leave to dry.