Prepare a firm dough with the flour, salt, a bit of warm water and vinegar. Knead very well and separate it into 6 pieces. Roll three of the pieces with a rolling pin to make round pita shapes. Join the first three pitas by placing one on top of the other after you have brushed them with oil.
Press down to join them well, and use the rolling pin to make one thicker sheet of pastry. Make another sheet in the same manner. To prepare the filling: place all the greens in a large mixing bowl and sprinkle with salt. Take small portions into your hands and squeeze to get rid of excess water.