Sift flour and mix with yoghurt and soda. Knead well together. Heat olive oil until almost smoking. Drop dough by the teaspoonful into hot oil. Fry only a few at a time. They quickly rise to the surface, brown, and are ready to be skimmed out of the fat.
Drain on absorbent paper. When all are fried, dip a few at a time in thin syrup. Serve them hot or cold.