Combine the tahini with icing sugar and water. Add the flour, salt, vanilla and cocoa, mix to form a dough. Wrap the dough in cling film and chill for approx. 1 hr.
To shape & bake
Shape the dough into approx. 20 equal balls, roll in the sesame seeds. Space the balls out evenly on a baking tray lined with baking paper, flatten to a thickness of approx. 1 cm.
Bake for approx. 15 mins. in the centre of an oven preheated to 180°C.