Combine rice flour, wheat starch, salt and pepper in a mixing bowl. Pour in the hot water and mix until evenly blended.
Spoon this batter into small bowls until almost 80% full. Steam the pudding over rapidly boiling water for 20-25 minutes until set.
To prepare topping: Heat oil and sesame oil in a non-stick saucepan. Sauté dried shrimp until fragrant. Add preserved radish and continue to fry for a while. Add mushrooms and sausage. Toss well to combine.
Spoon about a tablespoon of the topping over the rice kuih and continue to steam for a further 4-5 minutes. Remove from heat and leave to cool. Sprinkle with a little of the garnish over the pudding before serving.