Mix rice flour, salt and tapioca flour. Add 400ml cold water firstly and mix well. Strain to avoid any possible bumps. Then add 150ml hot boiling water. Mix well and set aside for 30 minutes.
Bring a large pot of water to a boiling and setup the steamer, (steam the pans firstly in cold winter day).
Use a kitchen paper to grease the pan, then gently stir the batter and place in around 1/3 cup (depending on the size of the pan, mine is 26cm in diameter make adjustment after the first steaming), better via a fine strainer to form a thin cover. Don't let the wrapper too thick, otherwise can't be steamed well. Place the pan to steam for 3-4 minutes, covered and over high fire until there are large bubbles formed (showing the noodles are well steamed). Transfer out and place in cold water for cooling and brush oil on surface. During the process, stir the batter once again and pour in the second pan, add the second pan to steam.
Peel from the thicker edges, cool down. Re-peat the process until finish all of the batter. Remember to stir the batter evenly before using.
Fold the steamed sheets and cut into strips(either thin or wide).