Half fill a large deep saucepan with oil and preheat it to 375 degrees. Sift together the flour, salt, baking powder and cinnamon into a large mixing bowl. In a separate bowl, beat the egg well, then beat in the sugar, milk, and vanilla. Pour the egg mixture into flour and mix slightly until moistened.
Turn onto a floured surface and knead lightly. Roll the dough out to a 1/4-inch thickness. Slice into diamond shapes about 3-inches long.
Fry in oil, turning once, until they are golden brown and puffed up. Remove, drain on paper towels and sprinkle with powdered sugar. Serve immediately with cafe au laite.