Heat the oil in a deep heavy-bottomed saucepan, until very hot or until a breadcrumb sizzles in it (CAUTION: Hot oil is very dangerous. Do not leave unattended).
Mix the cinnamon and sugar together in a bowl.
Carefully lower the tortilla ribbons into the hot oil and deep-fry until crisp and golden. Carefully remove with a slotted spoon and drain on kitchen paper. Sprinkle with the cinnamon sugar while still hot.
Serve piled up in a bowl with a spoon of yoghurt on top