Soften the sourdough by kneading the previous evening. The next day, pour a cup of water into a pan and boil the aniseed. Add the sugar, stirring to dissolve. Cool to lukewarm. Place the sourdough in a bowl; add the olive oil, lukewarm aniseed mixture, salt and flour. Knead thoroughly until the dough becomes smooth and elastic.
Take a fistful of dough (about the size of an orange) and set aside. Allow the dough to rise until about double in size. When the dough has risen, place it in a well-oiled round baking tray and shape the fistful of dough (previously set aside ) into a long strand. Cut the strand in the middle and lay on the dough in the baking tray in such a way as to form a cross.
Place a walnut in the centre and at each of the four ends of the cross or create various representations (ploumidia) to decorate the loaf. Brush the dough with the milk and sprinkle with sesame seeds. Bake in a hot oven at 200°C for 15 minutes, then cover the loaf and continue to bake at 180°C for a further 35-40 minutes.