In a bowl, combine sugar and cinnamon. Coat bottom of medium-sized frying pan with 1/4 inch of oil. Heat oil until hot (but not too hot or bunuelos will burn). Cut flour tortillas into small triangles. I like to use a cookie cutter in various shapes to make them look a little fancier. In small batches, fry the flour tortillas until they are golden brown. Remove from oil with a slotted spoon and transfer to a plate lined with paper towels to drain. While still warm, transfer to the bowl with the cinnamon and sugar mixture to coat and serve.