PUT glutinous rice in a basin. Add just enough water to cover the rice. Stir in alkaline water. Soak rice for a minimum of 3 1/2-4 hours. Drain then add corn oil and divide rice into 15 equal portions. Set aside.
Divide red bean paste or lotus paste into 15 equal portions. Put a quarter piece of salted egg yolk in the centre and roll into a round ball.
Fold each single bamboo leaf into a cone. Fill up with 1 heaped tablespoon of glutinous rice and add one portion of prepared filling. Cover with the rest of each divided portion of glutinous rice. Fold over to cover the rice to form a triangle-shaped dumpling.
Fill half a saucepot with water and bring to a boil. Put dumplings into the pot and cook for 1 1/2-2 hours on medium heat.
Add a pinch of borax if you want the cooked dumplings to have a shiny look and spongy texture.