1. In a mortar or blender, place the mastic gum and mahlab grains and grind them. In a bowl, add the semolina, sugar, cinnamon, cloves, and the ground mastic and mahlab, and mix well.
2. Add the sourdough starter and the lukewarm water, and knead thoroughly until you have a soft dough. Take a piece of dough and roll it into a log shape. Dip it into the sesame seeds and then roll it so the sesame seeds stick all over. Shape the cookies into various designs and place them on a baking tray lined with non-stick parchment paper.
3. Cover the cookies and let them rest for 2-3 hours to rise. Preheat the oven to 180°C (350°F) and bake for 50 minutes or until golden brown. Alternatively, you can bake them in a wood-fired oven.
