Add the baking soda to the yogurt, then put the egg, sugar and the oil. Stir well and add the flour. Does not intervene, and stirred so as to obtain a thick slurry. Spoon take a little of the mixture and place on tray (tray does not spread with sunflower oil, or sprinkle with flour). Sprinkle cookies with sugar. Since not interfere cookies do not become balls and gently shows bleeding. Bake at 200-220 S.