In a large bowl combine rice flour, tapioca flour, and 1/4 teaspoon salt. Make a well in the center and pour in 1/2 the warm water.
Using your hands stir the ingredients together kneading the dough until it is well combined. Now add the rest of the water, use a wooden spoon to stir it all together until you achieve a fine liquid batter.
Add 2 teaspoons vegetable oil and allow the batter to rest for 15 minutes.
Bring a steamer pot to rapid boil, place as many ramekins to the steamer tray as you can. Now fill each ramekin with the batter 2/3 full. Cover and steam for 5 minutes. Repeat this process until batter is finished.
Pound the cooked prawns in a mortar and pestle until crushed.
Put a fry pan on low heat, add the crushed prawns, garlic, and shallots, stir fry for 5 minutes or until prawns are completely dry and floss-like texture.