In a medium bowl, dissolve the yeast in the lukewarm water. Stir in 1 cup of the flour, then add the sugar, dried cranberries (if using) and oil and stir in. Incorporate a second cup of flour, then turn the dough out onto a well-floured surface and knead for 5 minutes, or until smooth
Cover the dough with plastic wrap and let rise for 2 to 3 hours, until doubled in volume. Meanwhile stir the tahini and sugar until mix together. Set aside
Meanwhile, place a baking stone or unglazed quarry tiles, if you have them, (or a baking sheet) on the middle oven rack and preheat the oven to 375 F. Mix together the tahini and sugar and stir until smooth. Set aside
Cut the dough into 6 equal pieces. Work with 3 at a time, keeping the others covered. Flatten each out on a lightly floured surface, then roll each out to a rectangle about 5 inches by 10 inches. Spread the top surface with 2 1/2 tbsp of the filling mixture, spreading it almost to the edges. Roll up the rectangle from a long side into a cylinder, which will stretch as you roll to about 20 inches long. Anchor one end and coil the bread around itself, then tuck the end in Flatten with the palm of your hand, then set aside, covered, while you fill and shape the other 2 rectangles
Return the first coil and roll out gently with a rolling pin. Roll the other 2 out a little and then return to the first one and roll it out a little more thinly, and so on, until you have rolled each to a round about 6 to 7 inches in diameter. A little filling may leak out- don't worry, just leave it
Place the bread on the hot baking stone or tiles (or baking sheet) and bake for 15 to 20 minutes, until golden brown and flaky. Transfer to a rack to cool
Shape and bake the remaining 3 pieces of dough. Serve warm or at room temperature