Take boiling water in a medium pot and add the rice. Stir and cover the lid. Turn the heat down to low and simmer until the rice is mushy. When the rice is done add milk to the pot and turn the heat up to the medium. Stir occasionally until it is boiling. Add sugar and stir. Take rice flour and corn starch in a bowl and add 1/3 cup of cold water and whisk it until smooth. Add this to the pot slowly while whisking the pudding constantly. Cook it for another 5 minutes and turn the heat off. Add vanilla sugar and stir. Apportion the pudding into bowls and let them sit on the counter top until they are cool enough. Sprinkle ground cinnamon and chopped walnut on top. Chill them in the refrigerator.