Christopsomo from Crete

Make the starter: In a large bowl dissolve the yeast in 1 cup hot water and add 1 cup flour. Mix well, cover the bowl, allowing the yeast to rise for an hour. Add 1 cup sugar, ½ cup oil, the orange juice and 1 cup flour. Mix with a wooden spoon, add more flour if necessary in order to make a soft dough. Knead until smooth. Let sit covered in a warm place until doubled in bulk, it approx. 2 hours.
Using a pestle and mortar grind the mastic crystals with 1 tsp sugar. In another bowl, large enough to fit all the remaining ingredients, mix the rest of the flour, 2 cups sugar and the spices. Create a well in the middle and place the starter there. Start kneading, working progressively and adding the rest of the water in doses until you get a firm yet smooth dough. Continue kneading, either by hand on a floured surface, or in a mixer with a dough hook (you might need to divide the dough mass to fit inside the mixer bowl). Knead til smooth, about 10-12 minutes. Add flour as needed to achieve the desired silky, nonsticky texture. Place the dough in an oiled bowl, cover with plastic wrap and leave to rise, about 2 hours, until doubled in bulk. You can also divide the dough and knead two or four pieces separately, leaving them, if desired in the same oiled bowl in separate ones.
Once the dough has risen, punch it down again gently. Depending on whether you’ve kept one big piece or four smaller ones, divide so that there are eight equal balls all together. Shape these into ropes about 20 cm / 8 inches long. Take two per loaf and shape into a cross, pressing to secure in the middle. Let rest in oiled pans, covered with a kitchen towel, until doubled in bulk, about 1 hour or so. Press a whole walnut into the middle and bake in a preheated oven at 200ºC / 390ºF. Brush with an egg wash and sprinkle with sesame seeds. Bake til golden, about 40 minutes. Cool on a wire rack and serve. Wrapped well in cling film, the breads will last for about a week. Or, wrap well and freeze.