Blend egg, rice flour, milk, and oil.
Combine flour, granulated sugar, baking powder, cinnamon, and salt.
Stir into egg mixture just till moistened.
Shape the batter into doughnuts and into deep hot fat (375°).
Fry till golden, about 1 1/2 minutes per side.
Drain on paper toweling.
Dip in powdered sugar.