Place all ingredients into a container. Stir until a smooth, lump-free rice batter is formed. Cover with plastic wrap and let it ferment at room temperature. The fermented batter will have numerous small holes on its surface. Heat a flat pan over low heat and use a brush to apply a thin layer of oil. Ladle one scoop of the rice batter into the pan and spread it into a round shape. As the batter gradually solidifies, small pores will appear on the surface. Cover the pan and let it steam briefly.
