Sprinkle the yeast over the water and set aside in a warm place until foamy, about 10 minutes. Whisk in 2 tablespoons of the olive oil and the salt. Sift the flour into a large mixing bowl, make a well in the center, and pour in the yeast mixture. Knead 10 minutes, adding additional flour if necessary to make a firm elastic dough. Transfer to a lightly oiled bowl, tightly cover with plastic wrap, and set aside for 2 hours in a warm draft-free spot. Knead in the rigani, mint, and feta until evenly distributed throughout the dough. Lightly oil a heavy baking sheet and place the dough in the center. Form into a round loaf and flatten to a thickness of 5 cm. Cover with a clean kitchen towel and set aside for 1 hour in a warm draft-free spot. The dough will rise only slightly. Heat the oven to 180ºC . With a sharp thin blade, slash the top of the loaf diagonally in 2 or 3 parallel lines, brush with the remaining olive oil, and bake 25 minutes. Brush with the beaten egg yolk and bake 15 minutes longer, or until the bread is deep golden brown and sounds hollow when tapped on the bottom.